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Do stimulants increase the IQ tests score for everyone?

Do stimulants increase the IQ tests score for everyone?


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There is some meta-analytic evidence that stimulants increase the IQ test scores of ADHD children by 2 to 7 points (Jepsen et al., 2009). Although giving stimulants to non-ADHD children may be unethical, I'm still wondering if there is improvement in IQ test score in children (or adults) who do not meet the criteria for an ADHD diagnosis. An additional motivation for asking this is that a study by Tsai et al. (2013) found that the IQ test score improvement from methylphenidate "had no correlation with the decrement of ADHD symptoms."

Jepsen, J. R. M., Fagerlund, B., & Mortensen, E. L. (2009). Do attention deficits influence IQ assessment in children and adolescents with ADHD?. Journal of Attention Disorders, 12(6), 551-562.
Tsai, C. S., Huang, Y. S., Wu, C. L., Hwang, F. M., Young, K. B., Tsai, M. H., & Chu, S. M. (2013). Long-term effects of stimulants on neurocognitive performance of Taiwanese children with attention-deficit/hyperactivity disorder. BMC psychiatry, 13(1), 330.


IQ in ADHD sufferers indeed increases with the treatment of stimulants, such as methylphenidate (Meyes et al., 1994). This is thought to rely on the attention-narrowing effect of stimulants, i.e., they cause the easily distracted ADHD child to focus better on the IQ task (Aman, 1996).

It is an interesting question indeed whether such an effect also plays a role in healthy controls. Indeed it does, at least according to one study, where a control population was subjected to amphetamine.

  • Amphetamine improves performance on spatial working memory, Stroop tasks and enhances language production (Barch & Carter, 2005). The authors did, however, not measure performance on full blown IQ tests.

References
- Aman, J Development Phys Disabil (1996); 8(4): 347-65
- Barch & Karter, Schizophrenia Res (2005); 77(1): 43-58
- Meyes et al., DMCN (1994); 36(12): 1099-107


Not about IQ as a whole alas, but I found a 2010 systematic review & meta-analysis "Modafinil and methylphenidate for neuroenhancement in healthy individuals: A systematic review", apparently the only systematic one to date on methylphenidate in healthy subjects:

The term neuroenhancement refers to improvement in the cognitive, emotional and motivational functions of healthy individuals through, inter alia, the use of drugs. Of known interventions, psychopharmacology provides readily available options, such as methylphenidate and modafinil. Both drugs are presumed to be in widespread use as cognitive enhancers for non-medical reasons. Based on a systematic review and meta-analysis we show that expectations regarding the effectiveness of these drugs exceed their actual effects, as has been demonstrated in single- or double-blind randomised controlled trials. Only studies with sufficient extractable data were included in the statistical analyses. For methylphenidate an improvement of memory was found, but no consistent evidence for other enhancing effects was uncovered. Modafinil on the other hand, was found to improve attention for well-rested individuals, while maintaining wakefulness, memory and executive functions to a significantly higher degree in sleep deprived individuals than did a placebo. However, repeated doses of modafinil were unable to prevent deterioration of cognitive performance over a longer period of sleep deprivation though maintaining wakefulness and possibly even inducing overconfidence in a person's own cognitive performance.

Somewhat similarly, there's another more recent (2014) review of methylphenidate "Cognitive effects of methylphenidate in healthy volunteers: a review of single dose studies" (MPH), but its methodology is limited to "effective study percentage" (i.e. not fully meta-analytical):

The studies reviewed here show that single doses of MPH improve cognitive performance in the healthy population in the domains of working memory (65% of included studies) and speed of processing (48%), and to a lesser extent may also improve verbal learning and memory (31%), attention and vigilance (29%) and reasoning and problem solving (18%), but does not have an effect on visual learning and memory. MPH effects are dose-dependent and the dose-response relationship differs between cognitive domains. MPH use is associated with side effects and other adverse consequences, such as potential abuse. Future studies should focus on MPH specifically to adequately asses its benefits in relation to the risks specific to this drug.

If one is willing to consider modafinil in this class of drugs (some have labelled it "atypical DAT-inhibitor"), then there's a newer 2015 review "Modafinil for cognitive neuroenhancement in healthy non-sleep-deprived subjects: A systematic review":

We found that whilst most studies employing basic testing paradigms show that modafinil intake enhances executive function, only half show improvements in attention and learning and memory, and a few even report impairments in divergent creative thinking. In contrast, when more complex assessments are used, modafinil appears to consistently engender enhancement of attention, executive functions, and learning.

All reviews primarily point to memory effects (in the short term, laboratory tests), although the last review (modafinil-only) has more mixed results in that regard. The other potential effects of MPH on IQ like speed of processing, are less convincing.

Although I was asking about IQ here, the long-term effects analyzed in the second review raise interesting questions about the mediating mechanism for the broader enhancement effects like learning (these "neuroenhancers" being popular as "study drugs"). There's a different line of research indicating that stimulants may affect motivation even more than mere cognition, even for "healthy" individuals, although apparently only in some sub-groups… which raises other interesting questions (sub-clinical attention problems, personality factors, etc.)

Actually, the authors is this last line of research have conducted their own (2015) meta-analysis of MPH and amphetamine: "Prescription Stimulants' Effects on Healthy Inhibitory Control, Working Memory, and Episodic Memory: A Meta-analysis.":

The present meta-analysis was conducted to estimate the magnitude of the effects of methylphenidate and amphetamine on cognitive functions central to academic and occupational functioning, including inhibitory control, working memory, short-term episodic memory, and delayed episodic memory. In addition, we examined the evidence for publication bias. Forty-eight studies (total of 1,409 participants) were included in the analyses. We found evidence for small but significant stimulant enhancement effects on inhibitory control and short-term episodic memory. Small effects on working memory reached significance, based on one of our two analytical approaches. Effects on delayed episodic memory were medium in size. However, because the effects on long-term and working memory were qualified by evidence for publication bias, we conclude that the effect of amphetamine and methylphenidate on the examined facets of healthy cognition is probably modest overall. In some situations, a small advantage may be valuable, although it is also possible that healthy users resort to stimulants to enhance their energy and motivation more than their cognition.

Its results are mostly in line with previous conclusions (memory being the main aspect improved), however it emphasized that effect size is small (for short-term effects), and it also found publication bias for long-term effects.

After writing that, I found another 2015 review which mostly summarizes what I said by going over those meta-analyses, but emphasizes memory effects and doesn't dig much the motivation explanation.

Finally, I found a 2017 RCT on chess performance (which is reasonably correlated with IQ, at least for non-top players) and psychostimulants. The results of this study are not straightforward:

This study investigated whether performance in chess - a competitive mind game requiring highly complex cognitive skills - can be enhanced by methylphenidate, modafinil or caffeine. In a phase IV, randomized, double-blind, placebo-controlled trial, 39 male chess players received 2×200 mg modafinil, 2×20 mg methylphenidate, and 2×200 mg caffeine or placebo in a 4×4 crossover design. They played twenty 15-minute games during two sessions against a chess program (Fritz 12; adapted to players' strength) and completed several neuropsychological tests. Marked substance effects were observed since all three substances significantly increased average reflection time per game compared to placebo resulting in a significantly increased number of games lost on time with all three treatments. Treatment effects on chess performance were not seen if all games (n=3059) were analysed. Only when controlling for game duration as well as when excluding those games lost on time, both modafinil and methylphenidate enhanced chess performance as demonstrated by significantly higher scores in the remaining 2876 games compared to placebo. In conjunction with results from neuropsychological testing we conclude that modifying effects of stimulants on complex cognitive tasks may in particular result from more reflective decision making processes. When not under time pressure, such effects may result in enhanced performance. Yet, under time constraints more reflective decision making may not improve or even have detrimental effects on complex task performance.

Quite an interesting conclusion: to me it suggests that modafinil and MPH enhance exploitation rather than exploration.


Can They Measure Intelligence?

As we already stated, the validity and accuracy of IQ tests are questionable and the more you think about it the harder the answer to the titular question seems to be. In reality, they are valid measures of a person’s intelligence but only when they are carried out and interpreted correctly. Since they measure a variety of different skills through the solving of various problems, including memory, reasoning, verbal comprehension, the tests appear to be the logical way of determining how well-equipped somebody’s mind is.

In reality, experts and scientists believe that the IQ tests as we know them and use them today are still lacking and are actually not well equipped to give us meaningful and useful scores for the separate abilities they are testing. The only way they should be interpreted and understood is when measuring the general intelligence and capabilities of the person. But this is the exact problem because how can something be accurate if the means of calculating it does not seem to be doing its job?

Among the most stated issues with IQ tests is the fact that a person’s IQ score can change in different contexts. A discussed motivation, readiness, and even practice play a huge role so one can increase their chances at a higher score by doing enough tests and learning the ropes of how they operate. If one tries less, they will not score high and others will deem them unintelligent for years. In much the same way, if it is your first time and you are motivated but lack the strategies people often use to score higher, you will again come out with a lot score and think of yourself as somebody with subpar intellectual capabilities.

Measurements and factors also tend to be biased to a certain degree. Some ethnic or racial groups perform worse on average on certain questions that are too specific for certain believes or cultures but are at the same time taken as a standard. This type of bias is present less and less however as the makers of tests actively remove the questions ad problems of this nature. Still, though, it is the belief of many experts from the psychology field that a lot of tests are linguistically, economically, and culturally biased against minorities, especially Black and Hispanic peoples.


Measuring Intelligence: Standardization and the Intelligence Quotient

The goal of most intelligence tests is to measure “g,” the general intelligence factor. Good intelligence tests are reliable, meaning that they are consistent over time, and also demonstrate validity, meaning that they actually measure intelligence rather than something else. Because intelligence is such an important individual difference dimension, psychologists have invested substantial effort in creating and improving measures of intelligence, and these tests are now considered the most accurate of all psychological tests. In fact, the ability to accurately assess intelligence is one of the most important contributions of psychology to everyday public life.

Intelligence changes with age. A 3-year-old who could accurately multiply 183 by 39 would certainly be intelligent, but a 25-year-old who could not do so would be seen as unintelligent. Thus understanding intelligence requires that we know the norms or standards in a given population of people at a given age. The standardization of a test involves giving it to a large number of people at different ages and computing the average score on the test at each age level.

It is important that intelligence tests be standardized on a regular basis, because the overall level of intelligence in a population may change over time. The Flynn effect refers to the observation that scores on intelligence tests worldwide have increased substantially over the past decades (Flynn, 1999). Although the increase varies somewhat from country to country, the average increase is about 3 IQ points every 10 years. There are many explanations for the Flynn effect, including better nutrition, increased access to information, and more familiarity with multiple-choice tests (Neisser, 1998). But whether people are actually getting smarter is debatable (Neisser, 1997).

Once the standardization has been accomplished, we have a picture of the average abilities of people at different ages and can calculate a person’s mental age, which is the age at which a person is performing intellectually. If we compare the mental age of a person to the person’s chronological age, the result is the intelligence quotient (IQ), a measure of intelligence that is adjusted for age. A simple way to calculate IQ is by using the following formula:

IQ = mental age ÷ chronological age × 100.

Thus a 10-year-old child who does as well as the average 10-year-old child has an IQ of 100 (10 ÷ 10 × 100), whereas an 8-year-old child who does as well as the average 10-year-old child would have an IQ of 125 (10 ÷ 8 × 100). Most modern intelligence tests are based on the relative position of a person’s score among people of the same age, rather than on the basis of this formula, but the idea of an intelligence “ratio” or “quotient” provides a good description of the score’s meaning.

Wechsler Scales

The Wechsler Adult lntelligence Scale (WAIS) is the most widely used intelligence test for adults (Watkins, Campbell, Nieberding, & Hallmark, 1995). The current version of the WAIS, the WAIS-IV, was standardized on 2,200 people ranging from 16 to 90 years of age. It consists of 15 different tasks, each designed to assess intelligence, including working memory, arithmetic ability, spatial ability, and general knowledge about the world. The WAIS-IV yields scores on four domains: verbal, perceptual, working memory, and processing speed. The reliability of the test is high (more than 0.95), and it shows substantial construct validity. The WAIS-IV is correlated highly with other IQ tests such as the Stanford-Binet, as well as with criteria of academic and life success, including college grades, measures of work performance, and occupational level. It also shows significant correlations with measures of everyday functioning among people with intellectual disabilities.

Video 7.1.1. Brain vs. Bias provides an overview of the WAIS & WISC tests, standardization and validity, and IQ performance.

The Wechsler scale has also been adapted for preschool children in the form of the Wechsler primary and preschool scale of intelligence-fourth edition (WPPSI-IV) and for older children and adolescents in the form of the Wechsler intelligence scale for children-fifth edition (WISC-V).

Figure 7.1.1. Examples of the types of items you might see on an intelligence test.

Bias in Intelligence Testing

Intelligence tests and psychological definitions of intelligence have been heavily criticized since the 1970s for being biased in favor of Anglo-American, middle-class respondents and for being inadequate tools for measuring non-academic types of intelligence or talent. Intelligence changes with experience, and intelligence quotients or scores do not reflect that ability to change. What is considered smart varies culturally as well, and most intelligence tests do not take this variation into account. For example, in the West, being smart is associated with being quick. A person who answers a question the fastest is seen as the smartest, but in some cultures, being smart is associated with considering an idea thoroughly before giving an answer. A well- thought out, contemplative answer is the best answer.

Video 7.1.2. Intelligence explains the different definitions of intelligence and the nature/nurture debate in the context of intelligence.


14 Signs of High Intelligence. Do you show these?

Home » The human condition » 14 Signs of High Intelligence. Do you show these?

Without taking an Intelligence Quotient test, what traits, thoughts patterns, or behaviors would a high IQ person show?

When we observe or interact with people, we don’t typically know their IQ score. We observe their behavior, learn their history, and judge what they say or do. We look for observable signs of intelligence that seem practical, not theoretical.


Are Humans Getting Smarter or Dumber?

Is humanity getting smarter or dumber with time? The answer may be both.

While IQ scores are rising at a remarkable rate, humans' underlying genetic potential for smarts could be on the decline, a new study suggests. The research found that by one measure of intelligence, the Victorians had modern folk beat.

The findings aren't without controversy — particularly whether or not the measurements used really reveal intelligence. Still, the study highlights the trouble with measuring intelligence over time: Smarts aren't defined as just one thing. What makes a person clever on the African Savannah could be nearly useless in the financial centers of Hong Kong.

"It's not simply that intelligence is going down or going up," said Michael Woodley, a psychologist at Umea University in Sweden who led the new research. "Different parts of intelligence could be changing in lots of different ways." [Life's Extremes: Smart vs. Dumb]

Are you smarter than your grandma?

The world is full of evidence that modern humans have more going on upstairs than their ancestors did: Smartphones. Heart transplants. A basic understanding that germs cause diseases.

Beyond these technological advances, though, is another hint that humans are getting smarter. It's called the Flynn effect, named after intelligence researcher James Flynn, an emeritus professor of the University of Otago in New Zealand.

Since IQ, or intelligence quotient, tests have been revised and standardized several times in the past 100 years, to see the Flynn effect, scientists have their volunteers take tests designed for previous generations. Flynn and his colleagues have found that all around the world, the new generations score higher on the old tests than the original test takers did.

The increases are no small matter, either — they vary by geography, but tend to be around three extra IQ points per decade. [Creative Genius: The World's Greatest Minds]

Flynn and many other researchers suspect that rising IQ scores reflect improving modern environments. IQ is part heritable and part environmental enrich a young child's environment with opportunities to learn, and they'll have a higher IQ later in life. Better nutrition, more schooling and more stimulation could also explain the Flynn effect.

So could the kind of thinking that people do today. If you asked someone in the 19th century the relationship between a dog and a hare, they'd likely go with something concrete, based on their real-life experience with the two animals, Woodley said. "The dog hunts the hare" might be a typical response.

Today, people are taught to think more abstractly. A modern person would be more likely to say that both dogs and hares are mammals, for example.

"These sort of heuristics and modern habits of thought have changed the way people have approached answering IQ tests," Woodley said.

The dulling of humanity

Even as the Flynn effect sends IQ scores skyrocketing, some researchers argue a darker view. Humans aren't getting smarter, they say. They're getting stupider.

In November 2012, Stanford University School of Medicine researcher Gerald Crabtree published two papers in the journal Trends in Genetics suggesting that humanity's intelligence peaked between 2,000 and 6,000 years ago.

Crabtree based this assertion on genetics. About 2,000 to 5,000 genes control human intelligence, he estimated. At the rate at which genetic mutations accumulate, Crabtree calculated that within the last 3,000 years, all of humanity has sustained at least two mutations harmful to these intellect-determining genes (and will sustain a couple more in another 3,000 years). Not every mutation will cause harm — genes come in pairs, and some weaknesses caused by mutation can be covered for by the healthy half of the pair, Crabtree wrote but the calculation suggests that intelligence is more fragile than it seems.

Furthermore, he argued, intelligence isn't as evolutionarily important to humans today as it was when the species was hunter-gatherers. Thousands of years ago, failing to grasp the aerodynamics of throwing a spear when a lion was coming at you meant you were toast — no more passing along your genes to offspring. Modern man rarely faces such life-or-death tests of wits, Crabtree wrote. [10 Things That Make Humans Special]

Another theory holds that humanity's genetic capacity for intelligence is in decline because of a phenomenon called dysgenic mating. Since the mid-1800s, IQ and reproduction have been negatively correlated, studies have found. To put it bluntly, people who are more intelligent have fewer babies. Because intelligence is part genetic, some researchers argue that, if anything, IQs should be dropping.

Instead, scores are going up, creating a paradox for the dysgenic mating theory, Woodley said.

Understanding an intelligence paradox

Now, Woodley and his colleagues think they may have solved that paradox, and the news is not good.

To look back at historical intelligence, the researchers turned not to IQ tests, but to reaction time. Simple reaction time (the amount of time it takes to respond to a stimulus) is correlated with IQ, Woodley said, and not nearly as sensitive to cultural influences as IQ tests.

"The idea is that reaction times represent your ability to engage in very basic and elementary cognitive processing," he said. [The 10 Best Ways to Keep Your Mind Sharp]

In the 1880s, English scientist Sir Francis Galton measured reaction times in 2,522 young men and 888 young women from a wide variety of socioeconomic statuses. He found that men's average reaction time to a stimulus was 183 milliseconds, and women's was 187 ms. (Galton's reaction time studies were part of his work as the founder of the field of eugenics, the idea that only the "best" should reproduce. Eugenics was embraced by a variety of high-profile people in the early 1900s, most notably Adolf Hitler, who wanted to establish a "master race" of Aryans.)

Twelve similar studies to Galton's conducted after 1941, on the other hand, found an average reaction time for men of 250 ms and for women of 277 ms — markedly slower. A review study detailing those findings was published in The American Journal of Psychology in 2010.

Woodley and his colleagues expanded on the 2010 work, including additional data and matching the old and new studies to be sure they were measuring the same things. Despite the fact that timers have improved quite a bit since the 1880s, Woodley is confident that Galton's measurements are accurate. Galton used a pendulum-based machine to time reactions, and such machines are generally accurate within 10 ms, Woodley said.

Galton's data also behaves as you might expect it to behave if it were correct, Woodley said. For example, groups with more inbreeding performed worse on the reaction time test.

The new analysis was "crystal clear," Woodley said.

"We found a very, very robust trend with time, toward slowing speeds of reaction," he said, "which is consistent with the idea that the more stable, the more culturally neutral, the more genetically influenced components of intelligence have been declining rather than increasing."

What that suggests is that even as IQ scores rise with education and health, humanity's capacity to get smarter is shrinking. In essence, the Flynn effect might be hiding an underlying decline, a "psychometric dark matter" not visible on pen-and-paper intelligence tests, Woodley said.

"An analogy to use would be lower-quality seeds, but higher-quality fertilizers," he said, referring to this idea that a high-quality environment may be masking the decline in "smart" genes.

If true, the reasons are unknown. Possibilities range from exposure to neurotoxins in modern society to natural selection.

Smarter or dumber?

Not everyone sees the new reaction time findings as the final word, however.

"To sum up 100 years of research, there is a reliable correlation between measures of reaction time and measures of IQ, but the order of such correlations is far short of what would be required to use the former to explain the latter," said Theodore Nettelbeck, a psychologist at the University of Adelaide who researches intelligence.

In other words, Nettelbeck told LiveScience, using reaction time as a proxy for IQ leaves something to be desired. At best, he said, reaction times to complex stimuli might explain about 20 percent to 25 percent of the variation in IQs, and simple reaction times explain a lot less.

Nettelbeck also raised concerns about the various experiments analyzed in the new study and how comparable they might be.

"Not only would there be differences in the technologies for timing responses, which may or not influence the outcome measures there would also be procedural differences in the numbers of trials from which means [averages] have been derived, instructions to participants, extent of prior practice, the nature of stimuli, the form of response keys, all of which can influence the length of response," he said.

Reaction time can also be tricky to interpret, said James Flynn, for whom the Flynn effect is named.

"A dull person has just as quick a peak reaction time as a brilliant person," Flynn told LiveScience. The difference is that someone with a low IQ typically can't stay focused and so their reaction times won't be consistent throughout an experiment their scores vary more widely than those of high-IQ people.

"Is this really neural speed, or for a dull person, [or] is it much more difficult for them to be attentive to the task?" Flynn said.

Other factors play a role as well, he added. In studies of schoolchildren, kids in Hong Kong are quicker off the mark in reaction time tests than British kids. You could read those results to mean Chinese kids are smarter than Britons, Flynn said. Or perhaps Chinese kids are just more willing to take risks.

The good news is that even if Woodley and his colleagues are correct that the soil of the human mind is becoming less fertile, the species is not doomed to a slow decline into idiocy. Norway and Sweden are exceptions to the rule that less educated, lower-IQ people have more children, Flynn said. Both countries have few class differences and make birth control easily available. And with IQ scores still rising in most of the world, environment seems to be trumping possible genetic problems.

"Apparently, we haven't explored the limits of our genes yet," Flynn said.


What Does IQ Really Measure?

Kids who score higher on IQ tests will, on average, go on to do better in conventional measures of success in life: academic achievement, economic success, even greater health, and longevity. Is that because they are more intelligent? Not necessarily. New research concludes that IQ scores are partly a measure of how motivated a child is to do well on the test. And harnessing that motivation might be as important to later success as so-called native intelligence.

Researchers have long debated what IQ tests actually measure, and whether average differences in IQ scores--such as those between different ethnic groups--reflect differences in intelligence, social and economic factors, or both. The debate moved heavily into the public arena with the 1994 publication of The Bell Curve by Richard Herrnstein and Charles Murray, which suggested that the lower average IQ scores of some ethnic groups, such as African-Americans and Hispanics, were due in large part to genetic differences between them and Caucasian groups. That view has been challenged by many scientists. For example, in his 2009 book "Intelligence and How to Get It," Richard Nisbett, a psychologist at the University of Michigan, Ann Arbor, argued that differences in IQ scores largely disappear when researchers control for social and economic factors.

New work, led by Angela Lee Duckworth, a psychologist at the University of Pennsylvania, and reported online today in the Proceedings of the National Academy of Sciences explores the effect of motivation on how well people perform on IQ tests. While subjects taking such tests are usually instructed to try as hard as they can, previous research has shown that not everyone makes the maximum effort. A number of studies have found that subjects who are promised monetary rewards for doing well on IQ and other cognitive tests score significantly higher.

To further examine the role of motivation on both IQ test scores and the ability of IQ tests to predict life success, Duckworth and her team carried out two studies, both reported in today's paper. First, they conducted a "meta-analysis" that combined the results of 46 previous studies of the effect of monetary incentives on IQ scores, representing a total of more than 2000 test-taking subjects. The financial rewards ranged from less than $1 to $10 or more. The team calculated a statistical parameter called Hedge's g to indicate how big an effect the incentives had on IQ scores g values of less than 0.2 are considered small, 0.5 are moderate, and 0.7 or higher are large.

Duckworth's team found that the average effect was 0.64 (which is equivalent to nearly 10 points on the IQ scale of 100), and remained higher than 0.5 even when three studies with unusually high g values were thrown out. Moreover, the effect of financial rewards on IQ scores increased dramatically the higher the reward: Thus rewards higher than $10 produced g values of more than 1.6 (roughly equivalent to more than 20 IQ points), whereas rewards of less than $1 were only one-tenth as effective.

In the second study, Duckworth and her colleagues analyzed data from an earlier study of more than 500 boys from Pittsburgh, Pennsylvania, whose IQs were tested in the late 1980s by a team from the University of Wisconsin, Madison. During the IQ test, the boys, whose average age was 12.5 years, were videotaped then observers trained to detect signs of boredom and lack of motivation (such as yawning, laying their heads on the table, or looking often around the room) viewed the videos and assigned motivation scores.

Researchers followed the boys over time, and when the boys reached early adulthood (average age 24), 251 of them agreed to a series of interviews about their educational and job achievements (there were no differences in IQ or other key factors between those boys who participated and those who didn't.)

Duckworth's team analyzed the results of these earlier studies to see what they said about the relationship between motivation, IQ scores, and life success. By constructing a series of computer models of the data, the team found that higher motivation accounted for a significant amount of the differences in IQ scores and also in how well IQ predicted later success in life. For example, differences in motivation levels accounted for up to 84% of the differences between the boys in how many years of school they had completed or whether they had been able to find a job. On the other hand, motivation differences accounted for about only 25% of the differences in how well they had done in school as teenagers. According to the researchers, that suggests that native intelligence does still play an important role in both IQ scores and academic achievement.

Nevertheless, the Duckworth team concludes that IQ tests are measuring much more than just raw intelligence--they also measure how badly subjects want to succeed both on the test and later in life. Yet Duckworth and her colleagues caution that motivation isn't everything: The lower role for motivation in academic achievement, they write, suggests that "earning a high IQ score requires high intelligence in addition to high motivation."

The study has important social policy implications, Duckworth says. "I hope that social scientists, educators, and policy makers turn a more critical eye to any kind of measure, intelligence or otherwise," she says, adding that how hard people try "could be as important to success in life as intellectual ability itself." Duckworth suggests that admissions to programs for "gifted and talented" children should not be based on IQ scores alone, but also on "who wants to do the work."

Nisbett agrees that the study is "tremendously important in its implications." Motivation, along with self-discipline, "are crucial," Nisbett says. "A high IQ and a subway token will only get you into town."

Lex Borghans, an economist at the Maastricht University in the Netherlands, who has also studied the relationship between intelligence tests and economic success, says the new report shows that "both intelligence and personality matter." Even if native intelligence cannot be increased, Borghans says, "there might be other routes to success."


Ways to Inflate Your IQ

Many people think of IQ as a genetic trait, like brown eyes or short legs: You're born with it and you're stuck with it. Now, a growing body of research is showing that a person's IQ can rise—and even fall—over the years.

Scores can change gradually or quickly, after as little as a few weeks of cognitive training, research shows. The increases are usually so incremental that they're not immediately perceptible to individuals, and the intelligence-boosting effects of cognitive training can fade after a few months.

In the latest study, 33 British students were given IQ tests and brain scans at ages 12 to 16 and again about four years later by researchers at the Wellcome Trust Centre for Neuroimaging at University College London 9% of the students showed a significant change of 15 points or more in IQ scores.

On a scale where 90 to 110 is considered average, one student's IQ rose 21 points to 128 from 107, lifting the student from the 68th percentile to the 97th compared with others the same age, says Cathy Price, professor of cognitive neuroscience at the center and co-author of the study, published last month in Nature. Another student's score skidded out of the "high average" category, to 96 from 114.

Swings in individual IQ scores are often written off as the product of measurement error or a test subject having a bad day. But MRIs in this study showed changes in gray matter in areas corresponding to fluctuations in the kids' skills, Dr. Price says. Although the sample size is small, the study drew wide attention because it is among the first to show how changes in IQ scores may be reflected in actual shifts in brain structure.

Testing Cognitive Skills

Pre-employment tests measure some cognitive abilities that are similar to those gauged by IQ tests and are used for selecting employees for many kinds of jobs. Try some sample questions.

Take the Test

Try some sample questions from various IQ tests.

"There are many myths about IQ, such as the notion that IQ is a fixed number or that it is a crystal ball for future performance," says Eric Rossen, director of professional development and standards for the National Association of School Psychologists in Bethesda, Md.

The first reliable tests of intelligence in the U.S. were published in the early 1900s, says Alan S. Kaufman, clinical professor of psychology at Yale University and co-author of several IQ tests. Scores compare people to others of the same age based on a wide range of cognitive questions and tasks, from processing information and analyzing patterns, to solving age-appropriate math problems and recalling facts or vocabulary. A score in the 90 to 110 range is considered average. A "genius" may score 140 and above, he says.

IQ tests have been a target of ongoing criticism. Their use led to the misclassification of many children as "intellectually disabled" in the 1970s and 1980s. Similar cognitive tests used by employers to screen recruits have been attacked as discriminatory against African-American and Hispanic job candidates.

Today in schools, individual IQ-type tests are limited mainly to helping plan instruction for some children with specific learning disabilities and helping identify students for gifted programs. Kathleen Lundquist, president of APTMetrics, a Darien, Conn., human-resources consulting firm, says cognitive tests in the workplace today are often revised to eliminate adverse effects on minorities and are most often used as a screening tool for entry-level jobs.

There are practical steps people can take to see longer-term IQ changes. A 30-year study at the National Institute of Mental Health found that people whose work involves complex relationships, setting up elaborate systems or dealing with people or difficult problems, tend to perform better over time on cognitive tests. Test scores of people whose jobs are simple and require little thought actually tend to decline, according to the research, published in 1999 in Psychology and Aging.

New tasks stimulate the brain most. When researchers at the University of Hamburg subjected 20 young adults to one month of intense training in juggling, they found an increase in the corresponding gray matter in the brain as early as seven days after the training began. The added gray matter receded when the training was stopped, although the participants were still able to juggle, says the study, published in 2008 in PLoS One.

IQ tests don't measure such abilities as creativity, common sense or social sensitivity. They do assess many kinds of knowledge and abilities, including abstract reasoning skills. Rising scores in abstract reasoning are the main reason average IQ scores have been increasing by about three points every decade since the 1930s, based on studies by James Flynn, a professor emeritus of political studies at the University of Otago in New Zealand. That may be partly because children spend nearly twice as many years in school, on average, than children decades ago, says Wendy M. Williams, a professor in the department of human development at Cornell University.

Fluctuations in IQ scores over time underscore the brain-boosting benefits of a complex job, musical training, advanced schooling and new experiences throughout a lifetime.

Work & Family Mailbox

Schooling in general raises IQ by several points a year, based on research by Stephen Ceci, a professor of developmental psychology at Cornell, and others. "If you look at an IQ test, it asks things like, 'Who wrote Hamlet?' or 'Why do we pay for postage?' You are most likely to come across the answers in school," Dr. Ceci says. Even nonverbal abilities such as solving puzzles and spatial tasks may blossom because math classes today include visual reasoning with matrices, mazes, blocks or designs, he adds.

Intense training can raise scores. Using a method called "n-back," researchers at the University of Michigan had young adults practice recalling letter sequences by flashing a series of letters on a screen and asking them to press a key whenever they saw the same letter that appeared "n" times earlier, such as one or two times.

Training for about 25 minutes a day for eight to 19 days was linked to higher scores on tests of fluid intelligence, with gains increasing with the duration of the training, says Susanne Jaeggi, co-author of the study, published in 2008 in Proceeding of the National Academy of Sciences.

The gains tend to fade after practice stops, based on studies of children, Dr. Jaeggi says. "You need some booster sessions" to maintain improvements, she says. Other research has found training people to switch mental tasks quickly also can lift scores.

Music lessons are linked to higher IQ throughout life, according to research by E. Glenn Schellenberg, a psychology professor at the University of Toronto at Mississauga. Six years' lessons lifted children's IQ scores an average 7.5 points those gains eroded to two points by college age, says a study published in 2006 in the Journal of Educational Psychology.

In a study this year, researchers at the University of Kansas found practicing musicians who are active for a decade or more continue to post higher IQs beyond age 60.

Write to Sue Shellenbarger at [email protected]

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7.5 Measures of Intelligence

While you’re likely familiar with the term “IQ” and associate it with the idea of intelligence, what does IQ really mean? IQ stands for intelligence quotient and describes a score earned on a test designed to measure intelligence. You’ve already learned that there are many ways psychologists describe intelligence (or more aptly, intelligences). Similarly, IQ tests—the tools designed to measure intelligence—have been the subject of debate throughout their development and use.

When might an IQ test be used? What do we learn from the results, and how might people use this information? While there are certainly many benefits to intelligence testing, it is important to also note the limitations and controversies surrounding these tests. For example, IQ tests have sometimes been used as arguments in support of insidious purposes, such as the eugenics movement (Severson, 2011). The infamous Supreme Court Case, Buck v. Bell, legalized the forced sterilization of some people deemed “feeble-minded” through this type of testing, resulting in about 65,000 sterilizations (Buck v. Bell, 274 U.S. 200 Ko, 2016). Today, only professionals trained in psychology can administer IQ tests, and the purchase of most tests requires an advanced degree in psychology. Other professionals in the field, such as social workers and psychiatrists, cannot administer IQ tests. In this section, we will explore what intelligence tests measure, how they are scored, and how they were developed.

Measuring Intelligence

It seems that the human understanding of intelligence is somewhat limited when we focus on traditional or academic-type intelligence. How then, can intelligence be measured? And when we measure intelligence, how do we ensure that we capture what we’re really trying to measure (in other words, that IQ tests function as valid measures of intelligence)? In the following paragraphs, we will explore the how intelligence tests were developed and the history of their use.

The IQ test has been synonymous with intelligence for over a century. In the late 1800s, Sir Francis Galton developed the first broad test of intelligence (Flanagan & Kaufman, 2004). Although he was not a psychologist, his contributions to the concepts of intelligence testing are still felt today (Gordon, 1995). Reliable intelligence testing (you may recall from earlier chapters that reliability refers to a test’s ability to produce consistent results) began in earnest during the early 1900s with a researcher named Alfred Binet (Figure 7.13). Binet was asked by the French government to develop an intelligence test to use on children to determine which ones might have difficulty in school it included many verbally based tasks. American researchers soon realized the value of such testing. Louis Terman, a Stanford professor, modified Binet’s work by standardizing the administration of the test and tested thousands of different-aged children to establish an average score for each age. As a result, the test was normed and standardized, which means that the test was administered consistently to a large enough representative sample of the population that the range of scores resulted in a bell curve (bell curves will be discussed later). Standardization means that the manner of administration, scoring, and interpretation of results is consistent. Norming involves giving a test to a large population so data can be collected comparing groups, such as age groups. The resulting data provide norms, or referential scores, by which to interpret future scores. Norms are not expectations of what a given group should know but a demonstration of what that group does know. Norming and standardizing the test ensures that new scores are reliable. This new version of the test was called the Stanford-Binet Intelligence Scale (Terman, 1916). Remarkably, an updated version of this test is still widely used today.

In 1939, David Wechsler, a psychologist who spent part of his career working with World War I veterans, developed a new IQ test in the United States. Wechsler combined several subtests from other intelligence tests used between 1880 and World War I. These subtests tapped into a variety of verbal and nonverbal skills, because Wechsler believed that intelligence encompassed “the global capacity of a person to act purposefully, to think rationally, and to deal effectively with his environment” (Wechsler, 1958, p. 7). He named the test the Wechsler-Bellevue Intelligence Scale (Wechsler, 1981). This combination of subtests became one of the most extensively used intelligence tests in the history of psychology. Although its name was later changed to the Wechsler Adult Intelligence Scale (WAIS) and has been revised several times, the aims of the test remain virtually unchanged since its inception (Boake, 2002). Today, there are three intelligence tests credited to Wechsler, the Wechsler Adult Intelligence Scale-fourth edition (WAIS-IV), the Wechsler Intelligence Scale for Children (WISC-V), and the Wechsler Preschool and Primary Scale of Intelligence—IV (WPPSI-IV) (Wechsler, 2012). These tests are used widely in schools and communities throughout the United States, and they are periodically normed and standardized as a means of recalibration. As a part of the recalibration process, the WISC-V was given to thousands of children across the country, and children taking the test today are compared with their same-age peers (Figure 7.13).

The WISC-V is composed of 14 subtests, which comprise five indices, which then render an IQ score. The five indices are Verbal Comprehension, Visual Spatial, Fluid Reasoning, Working Memory, and Processing Speed. When the test is complete, individuals receive a score for each of the five indices and a Full Scale IQ score. The method of scoring reflects the understanding that intelligence is comprised of multiple abilities in several cognitive realms and focuses on the mental processes that the child used to arrive at his or her answers to each test item.

Interestingly, the periodic recalibrations have led to an interesting observation known as the Flynn effect. Named after James Flynn, who was among the first to describe this trend, the Flynn effect refers to the observation that each generation has a significantly higher IQ than the last. Flynn himself argues, however, that increased IQ scores do not necessarily mean that younger generations are more intelligent per se (Flynn, Shaughnessy, & Fulgham, 2012).

Ultimately, we are still left with the question of how valid intelligence tests are. Certainly, the most modern versions of these tests tap into more than verbal competencies, yet the specific skills that should be assessed in IQ testing, the degree to which any test can truly measure an individual’s intelligence, and the use of the results of IQ tests are still issues of debate (Gresham & Witt, 1997 Flynn, Shaughnessy, & Fulgham, 2012 Richardson, 2002 Schlinger, 2003).

What Do You Think?

Capital Punishment and Criminals with Intellectual Disabilities

The case of Atkins v. Virginia was a landmark case in the United States Supreme Court. On August 16, 1996, two men, Daryl Atkins and William Jones, robbed, kidnapped, and then shot and killed Eric Nesbitt, a local airman from the U.S. Air Force. A clinical psychologist evaluated Atkins and testified at the trial that Atkins had an IQ of 59. The mean IQ score is 100. The psychologist concluded that Atkins was “mildly mentally retarded.”

The jury found Atkins guilty, and he was sentenced to death. Atkins and his attorneys appealed to the Supreme Court. In June 2002, the Supreme Court reversed a previous decision and ruled that executions of intellectually disabled criminals are ‘cruel and unusual punishments’ prohibited by the Eighth Amendment. The court wrote in their decision:

Clinical definitions of mental retardation require not only subaverage intellectual functioning, but also significant limitations in adaptive skills. Mentally retarded persons frequently know the difference between right and wrong and are competent to stand trial. Because of their impairments, however, by definition they have diminished capacities to understand and process information, to communicate, to abstract from mistakes and learn from experience, to engage in logical reasoning, to control impulses, and to understand others’ reactions. Their deficiencies do not warrant an exemption from criminal sanctions, but diminish their personal culpability (Atkins v. Virginia, 2002, par. 5).

The court also decided that there was a state legislature consensus against the execution of the intellectually disabled people and that this consensus should stand for all of the states. The Supreme Court ruling left it up to the states to determine their own definitions of mental retardation, a widely used term at the time, and intellectual disability. The definitions vary among states as to who can be executed. In the Atkins case, a jury decided that because he had many contacts with his lawyers and thus was provided with intellectual stimulation, his IQ had reportedly increased, and he was now smart enough to be executed. He was given an execution date and then received a stay of execution after it was revealed that lawyers for co-defendant, William Jones, coached Jones to “produce a testimony against Mr. Atkins that did match the evidence” (Liptak, 2008). After the revelation of this misconduct, Atkins was re-sentenced to life imprisonment.

Atkins v. Virginia (2002) highlights several issues regarding society’s beliefs around intelligence. In the Atkins case, the Supreme Court decided that intellectual disability does affect decision making and therefore should affect the nature of the punishment such criminals receive. Where, however, should the lines of intellectual disability be drawn? In May 2014, the Supreme Court ruled in a related case (Hall v. Florida) that IQ scores cannot be used as a final determination of a prisoner’s eligibility for the death penalty (Roberts, 2014).

The Bell Curve

The results of intelligence tests follow the bell curve, a graph in the general shape of a bell. When the bell curve is used in psychological testing, the graph demonstrates a normal distribution of a trait, in this case, intelligence, in the human population. Many human traits naturally follow the bell curve. For example, if you lined up all your female schoolmates according to height, it is likely that a large cluster of them would be the average height for an American woman: 5’4”–5’6”. This cluster would fall in the center of the bell curve, representing the average height for American women (Figure 7.14). There would be fewer women who stand closer to 4’11”. The same would be true for women of above-average height: those who stand closer to 5’11”. The trick to finding a bell curve in nature is to use a large sample size. Without a large sample size, it is less likely that the bell curve will represent the wider population. A representative sample is a subset of the population that accurately represents the general population. If, for example, you measured the height of the women in your classroom only, you might not actually have a representative sample. Perhaps the women’s basketball team wanted to take this course together, and they are all in your class. Because basketball players tend to be taller than average, the women in your class may not be a good representative sample of the population of American women. But if your sample included all the women at your school, it is likely that their heights would form a natural bell curve.

The same principles apply to intelligence tests scores. Individuals earn a score called an intelligence quotient (IQ). Over the years, different types of IQ tests have evolved, but the way scores are interpreted remains the same. On most IQ tests, the average (or mean) IQ score is 100. Standard deviations describe how data are dispersed in a population and give context to large data sets. The bell curve uses the standard deviation to show how all scores are dispersed from the average score (Figure 7.15). In modern IQ testing, one standard deviation is 15 points. So a score of 85 would be described as “one standard deviation below the mean.” How would you describe a score of 115 and a score of 70? Any IQ score that falls within one standard deviation above and below the mean (between 85 and 115) is considered average, and 68% of the population has IQ scores in this range. An IQ score of 130 or above is considered a superior level.

Only 2.2% of the population has an IQ score below 70 (American Psychiatric Association [APA], 2013). If a person earns a score approximately two standard deviations below the mean on an intelligence test, (about 70 on a test with a mean of 100), has major deficits in adaptive functioning, and these cognitive and adaptive deficits were present before the age of 18, they could be diagnosed as having an intellectual disability (ID). Formerly known as mental retardation, the accepted term now is intellectual disability, and it has four subtypes: mild, moderate, severe, and profound (Table 7.4). The Diagnostic and Statistical Manual of Psychological Disorders lists criteria for each subgroup (APA, 2013).

Intellectual Disability Subtype Percentage of Population with Intellectual Disabilities Description
Mild 85% 3rd- to 6th-grade skill level in reading, writing, and math may be employed and live independently
Moderate 10% Basic reading and writing skills functional self-care skills requires some oversight
Severe 5% Functional self-care skills requires oversight of daily environment and activities
Profound <1% May be able to communicate verbally or nonverbally requires intensive oversight

On the other end of the intelligence spectrum are those individuals whose IQs fall into the highest ranges. Consistent with the bell curve, about 2% of the population falls into this category. People are considered gifted if they have an IQ score of 130 or higher, or superior intelligence in a particular area. Long ago, popular belief suggested that people of high intelligence were maladjusted. This idea was disproven through a groundbreaking study of gifted children. In 1921, Lewis Terman began a longitudinal study of over 1500 children with IQs over 135 (Terman, 1925). His findings showed that these children became well-educated, successful adults who were, in fact, well-adjusted (Terman & Oden, 1947). Additionally, Terman’s study showed that the subjects were above average in physical build and attractiveness, dispelling an earlier popular notion that highly intelligent people were “weaklings.” Some people with very high IQs elect to join Mensa, an organization dedicated to identifying, researching, and fostering intelligence. Members must have an IQ score in the top 2% of the population, and they may be required to pass other exams in their application to join the group.

Dig Deeper

What’s in a Name? Mental Retardation

In the past, individuals with IQ scores below 70 and significant adaptive and social functioning delays were diagnosed with mental retardation. When this diagnosis was first named, the title held no social stigma. In time, however, the degrading word “retard” sprang from this diagnostic term. “Retard” was frequently used as a taunt, especially among young people, until the words “mentally retarded” and “retard” became an insult. As such, the DSM-5 now labels this diagnosis as “intellectual disability.” Many states once had a Department of Mental Retardation to serve those diagnosed with such cognitive delays, but most have changed their name to Department of Developmental Disabilities or something similar in language. The Social Security Administration still uses the term “mental retardation” but is considering eliminating it from its programming (Goad, 2013). Earlier in the chapter, we discussed how language affects how we think. Do you think changing the title of this department has any impact on how people regard those with developmental disabilities? Does a different name give people more dignity, and if so, how? Does it change the expectations for those with developmental or cognitive disabilities? Why or why not?

Why Measure Intelligence?

The value of IQ testing is most evident in educational or clinical settings. Children who seem to be experiencing learning difficulties or severe behavioral problems can be tested to ascertain whether the child’s difficulties can be partly attributed to an IQ score that is significantly different from the mean for her age group. Without IQ testing—or another measure of intelligence—children and adults needing extra support might not be identified effectively. In addition, IQ testing is used in courts to determine whether a defendant has special or extenuating circumstances that preclude him from participating in some way in a trial. People also use IQ testing results to seek disability benefits from the Social Security Administration.

The following case study demonstrates the usefulness and benefits of IQ testing. Candace, a 14-year-old girl experiencing problems at school in Connecticut, was referred for a court-ordered psychological evaluation. She was in regular education classes in ninth grade and was failing every subject. Candace had never been a stellar student but had always been passed to the next grade. Frequently, she would curse at any of her teachers who called on her in class. She also got into fights with other students and occasionally shoplifted. When she arrived for the evaluation, Candace immediately said that she hated everything about school, including the teachers, the rest of the staff, the building, and the homework. Her parents stated that they felt their daughter was picked on, because she was of a different race than the teachers and most of the other students. When asked why she cursed at her teachers, Candace replied, “They only call on me when I don’t know the answer. I don’t want to say, ‘I don’t know’ all of the time and look like an idiot in front of my friends. The teachers embarrass me.” She was given a battery of tests, including an IQ test. Her score on the IQ test was 68. What does Candace’s score say about her ability to excel or even succeed in regular education classes without assistance? Why were her difficulties never noticed or addressed?


Does A High IQ Guarantee Success? Maybe Not

The Intelligence Quotient (IQ) doesn&rsquot measure what we know it measures what we are able to understand. An IQ test consists of a series of exams aimed at assessing how well we reason, process information, and solve problems relative to other people our age. Anyone scoring within 10 points of 100 is said to be of average intelligence, which makes someone who scores a 130 the smartest person in the room. That is, unless they&rsquore in a room with some certifiable genius types such as Einstein, Da Vinci, Plato, or Ivan Drago (aka Rocky Balboa&rsquos rival), who all have an IQ over 160. But even those with the gift of genius aren&rsquot handed a guarantee &mdash success, like batteries, is sold separately.

Smart from the Start &ndash Why it Matters

Since studying is unlikely to boost our IQ, being born with genius in our genes is kind of like hitting the intelligence lottery. Although it is possible to boost cognitive ability by learning new skills and playing problem-solving games, these changes are unlikely to increase overall IQ (sorry, Sudoku lovers). In this way, IQ is like physical health: We can exercise our brain and muscles to help them grow, but the changes aren&rsquot permanent the moment we stop exercising, our brains and muscles start to return to their original form Individual differences in working memory within a nomological network of cognitive and perceptual speed abilities. Ackerman PL, Beier ME, Boyle MO. School of Psychology, Georgia Institute of Technology. Journal of Experimental Psychology. 2002 Dec 131(4):567-89 .

If we assume we&rsquore all racing towards some version of &ldquosuccess,&rdquo a high IQ is one heck of a head start. But that doesn&rsquot mean we should give up just because our number falls a little lower on the scale. The first runner out of the blocks doesn&rsquot always win the race, and having the highest IQ in the crowd doesn&rsquot guarantee success. That&rsquos because there are some things an IQ test can&rsquot measure. For starters, there&rsquos no Street Smarts section on an IQ test, meaning a degree from the school of hard knocks doesn&rsquot carry much weight. Testing our reasoning also overlooks the various ways we learn: Some people can read and retain information while others need to get hands-on, and so on. One method isn&rsquot necessarily &ldquosmarter&rdquo than another they&rsquore just different.

IQ also overlooks what researcher Howard Gardner refers to as &ldquomultiple intelligences,&rdquo or the human capacity to possess a range of traits and abilities &mdash not all of which can be measured via testing. Similarly, the IQ test fails to measure traits such as creativity, imagination and innovation, all of which can contribute to a person&rsquos success (or lack thereof) The use of imagery by intelligent and by creative schoolchildren. Shaw GA. Journal of General Psychology. 1985 Apr 112(2):153-71 .

What iq can do for you &mdash and what it can&rsquot

Despite flaws in IQ testing, intelligence has been shown to play a role in determining achievement, business success, and even the rate of our mortality &mdash mostly because IQ strongly correlates with income Longitudinal cohort study of childhood IQ and survival up to age 76. Lawrence J Whalley, Ian J Deary. Department of Mental Health, University of Aberdeen. British Medical Journal. 2001 Jan . Having a high IQ also increases the likelihood of becoming a high-performer in a variety of aptitudes, from science to music. That&rsquos because a genius can process, store, and recall an absurd amount of highly complex information &mdash it&rsquos called working memory capacity The relationship between working memory capacity and executive functioning: evidence for a common executive attention construct. McCabe DP, Roediger HL, McDaniel MA, Balota DA, Hambrick DZ. Department of Psychology, Colorado State University. Neuropsychology. 2010 Mar 24(2):222-43 The generality of working memory capacity: a latent-variable approach to verbal and visuospatial memory span and reasoning. Kane MJ, Hambrick DZ, Tuholski SW, Wilhelm O, Payne TW, Engle RW. Department of Psychology, University of North Carolina at Greensboro. Journal of Experimental Psychology. 2004 Jun 133(2):189-217 .

But if being a brainiac was the one and only criterion for success, everyone with a lofty IQ would be wildly successful &mdash and obviously, that&rsquos not always the case. Even a genius can squander their intelligence jackpot Cognitive sophistication does not attenuate the bias blind spot. West RF, Meserve RJ, Stanovich KE. Department of Graduate Psychology, James Madison University. Journal of Personality and Social Psychology. 2012 Sep 103(3):506-19 . When smart people encounter a problem that needs solving, they tend to forgo facts in favor of mental shortcuts. Trouble is, these shortcuts can lead to foolish mistakes and ultimately the wrong answer. Turns out Mom was right: We can be too smart for our own good.

So if great intellect doesn&rsquot guarantee success, what factors separate an average Joe from a highly intelligent outlier? The real question becomes: Can we actually compete with genius by going from good to great?

The Genius Myth &mdash The Answer/Debate

Genius is real, but it can also be really misleading. For one thing, putting too much stake in &ldquogenius&rdquo implies the entire average-achieving population is virtually helpless. When taken at face value, the idea of innate intelligence plays into the genius myth. This legend would have us mere mortals believe that we either have it or we don&rsquot &mdash whatever &ldquoit&rdquo is. But when the curtain is pulled back, we see that genius is nothing more than a comforting parable. It comes in handy when trying to explain why some people seem to have it all, but it doesn&rsquot accurately depict the full scope and scale of human intelligence.

In reality, success is based on a whole lot more than genius alone. Persistence, practice, socio-emotional skills, our environment, the way we&rsquore raised, and luck all combine to determine what we will achieve Beyond IQ: broad-based measurement of individual success potential or &ldquoemotional intelligence&rdquo. Mehrabian A. Department of Psychology, University of California. Genetic, Social and General Psychology Monographs. 2000 May 126(2):133-239 . This explains why early interventions in child development so often improve individuals&rsquo chances of success &mdash our potential isn&rsquot fixed the day we&rsquore born rather, it&rsquos highly fluid and dependent on a number of both external and internal factors.

One of these factors &mdash grit &mdash has been shown to play a particularly big role when it comes to success. Grit is best defined as the perseverance and passion for a long-term goal. It&rsquos a single-minded focus that allows us to persist well beyond the point at which others would give up. One study found that West Point cadets and spelling bee superstars linked this grit factor with success time after time Grit: perseverance and passion for long-term goals. Duckworth AL, Peterson C, Matthews MD, Kelly DR. Department of Psychology, University of Pennsylvania. Journal of Personality and Social Psychology. 2007 Jun 92 (6):1087-101 . The soldiers and spellers who were most successful were more determined, had greater willpower, and exhibited better self-control than their lower-achieving peers. Researchers found that the smarter kids just didn&rsquot try as hard or want it as bad as the gritty kids Grit: perseverance and passion for long-term goals. Duckworth AL, Peterson C, Matthews MD, Kelly DR. Department of Psychology, University of Pennsylvania. Journal of Personality and Social Psychology. 2007 Jun 92 (6):1087-101 Role of test motivation in intelligence testing. Angela Lee Duckworth, Patrick D. Quinn, Donald R. Lynam, Rolf Loeber, and Magda Stouthamer-Loeberd. Department of Psychology, University of Pennsylvania. Psychological and Cognitive Sciences. 2011 April 25 . Grit and IQ are only weakly associated with each other, so a person doesn&rsquot need to be a genius to be gritty as all get out. I guess we could say it&rsquos better to be average and hardworking than to be a lazy genius.

Smart Versus Successful &mdash The Takeaway

When it comes determining to success, IQ isn&rsquot a promise, it&rsquos more of a performance enhancer. If genius is the elevator to the top, we&rsquoll just have to take the stairs. It may take longer, but it&rsquoll still get us to where we want to go.

Do you believe that a high IQ guarantees success? Share in the comments below!


Measuring Intelligence: Standardization and the Intelligence Quotient

The goal of most intelligence tests is to measure “g,” the general intelligence factor. Good intelligence tests are reliable, meaning that they are consistent over time, and also demonstrate validity, meaning that they actually measure intelligence rather than something else. Because intelligence is such an important individual difference dimension, psychologists have invested substantial effort in creating and improving measures of intelligence, and these tests are now considered the most accurate of all psychological tests. In fact, the ability to accurately assess intelligence is one of the most important contributions of psychology to everyday public life.

Intelligence changes with age. A 3-year-old who could accurately multiply 183 by 39 would certainly be intelligent, but a 25-year-old who could not do so would be seen as unintelligent. Thus understanding intelligence requires that we know the norms or standards in a given population of people at a given age. The standardization of a test involves giving it to a large number of people at different ages and computing the average score on the test at each age level.

It is important that intelligence tests be standardized on a regular basis, because the overall level of intelligence in a population may change over time. The Flynn effect refers to the observation that scores on intelligence tests worldwide have increased substantially over the past decades (Flynn, 1999). Although the increase varies somewhat from country to country, the average increase is about 3 IQ points every 10 years. There are many explanations for the Flynn effect, including better nutrition, increased access to information, and more familiarity with multiple-choice tests (Neisser, 1998). But whether people are actually getting smarter is debatable (Neisser, 1997).

Once the standardization has been accomplished, we have a picture of the average abilities of people at different ages and can calculate a person’s mental age, which is the age at which a person is performing intellectually. If we compare the mental age of a person to the person’s chronological age, the result is the intelligence quotient (IQ), a measure of intelligence that is adjusted for age. A simple way to calculate IQ is by using the following formula:

IQ = mental age ÷ chronological age × 100.

Thus a 10-year-old child who does as well as the average 10-year-old child has an IQ of 100 (10 ÷ 10 × 100), whereas an 8-year-old child who does as well as the average 10-year-old child would have an IQ of 125 (10 ÷ 8 × 100). Most modern intelligence tests are based on the relative position of a person’s score among people of the same age, rather than on the basis of this formula, but the idea of an intelligence “ratio” or “quotient” provides a good description of the score’s meaning.

Wechsler Scales

The Wechsler Adult lntelligence Scale (WAIS) is the most widely used intelligence test for adults (Watkins, Campbell, Nieberding, & Hallmark, 1995). The current version of the WAIS, the WAIS-IV, was standardized on 2,200 people ranging from 16 to 90 years of age. It consists of 15 different tasks, each designed to assess intelligence, including working memory, arithmetic ability, spatial ability, and general knowledge about the world. The WAIS-IV yields scores on four domains: verbal, perceptual, working memory, and processing speed. The reliability of the test is high (more than 0.95), and it shows substantial construct validity. The WAIS-IV is correlated highly with other IQ tests such as the Stanford-Binet, as well as with criteria of academic and life success, including college grades, measures of work performance, and occupational level. It also shows significant correlations with measures of everyday functioning among people with intellectual disabilities.

Video 7.1.1. Brain vs. Bias provides an overview of the WAIS & WISC tests, standardization and validity, and IQ performance.

The Wechsler scale has also been adapted for preschool children in the form of the Wechsler primary and preschool scale of intelligence-fourth edition (WPPSI-IV) and for older children and adolescents in the form of the Wechsler intelligence scale for children-fifth edition (WISC-V).

Figure 7.1.1. Examples of the types of items you might see on an intelligence test.

Bias in Intelligence Testing

Intelligence tests and psychological definitions of intelligence have been heavily criticized since the 1970s for being biased in favor of Anglo-American, middle-class respondents and for being inadequate tools for measuring non-academic types of intelligence or talent. Intelligence changes with experience, and intelligence quotients or scores do not reflect that ability to change. What is considered smart varies culturally as well, and most intelligence tests do not take this variation into account. For example, in the West, being smart is associated with being quick. A person who answers a question the fastest is seen as the smartest, but in some cultures, being smart is associated with considering an idea thoroughly before giving an answer. A well- thought out, contemplative answer is the best answer.

Video 7.1.2. Intelligence explains the different definitions of intelligence and the nature/nurture debate in the context of intelligence.


14 Signs of High Intelligence. Do you show these?

Home » The human condition » 14 Signs of High Intelligence. Do you show these?

Without taking an Intelligence Quotient test, what traits, thoughts patterns, or behaviors would a high IQ person show?

When we observe or interact with people, we don’t typically know their IQ score. We observe their behavior, learn their history, and judge what they say or do. We look for observable signs of intelligence that seem practical, not theoretical.


Can They Measure Intelligence?

As we already stated, the validity and accuracy of IQ tests are questionable and the more you think about it the harder the answer to the titular question seems to be. In reality, they are valid measures of a person’s intelligence but only when they are carried out and interpreted correctly. Since they measure a variety of different skills through the solving of various problems, including memory, reasoning, verbal comprehension, the tests appear to be the logical way of determining how well-equipped somebody’s mind is.

In reality, experts and scientists believe that the IQ tests as we know them and use them today are still lacking and are actually not well equipped to give us meaningful and useful scores for the separate abilities they are testing. The only way they should be interpreted and understood is when measuring the general intelligence and capabilities of the person. But this is the exact problem because how can something be accurate if the means of calculating it does not seem to be doing its job?

Among the most stated issues with IQ tests is the fact that a person’s IQ score can change in different contexts. A discussed motivation, readiness, and even practice play a huge role so one can increase their chances at a higher score by doing enough tests and learning the ropes of how they operate. If one tries less, they will not score high and others will deem them unintelligent for years. In much the same way, if it is your first time and you are motivated but lack the strategies people often use to score higher, you will again come out with a lot score and think of yourself as somebody with subpar intellectual capabilities.

Measurements and factors also tend to be biased to a certain degree. Some ethnic or racial groups perform worse on average on certain questions that are too specific for certain believes or cultures but are at the same time taken as a standard. This type of bias is present less and less however as the makers of tests actively remove the questions ad problems of this nature. Still, though, it is the belief of many experts from the psychology field that a lot of tests are linguistically, economically, and culturally biased against minorities, especially Black and Hispanic peoples.


Are Humans Getting Smarter or Dumber?

Is humanity getting smarter or dumber with time? The answer may be both.

While IQ scores are rising at a remarkable rate, humans' underlying genetic potential for smarts could be on the decline, a new study suggests. The research found that by one measure of intelligence, the Victorians had modern folk beat.

The findings aren't without controversy — particularly whether or not the measurements used really reveal intelligence. Still, the study highlights the trouble with measuring intelligence over time: Smarts aren't defined as just one thing. What makes a person clever on the African Savannah could be nearly useless in the financial centers of Hong Kong.

"It's not simply that intelligence is going down or going up," said Michael Woodley, a psychologist at Umea University in Sweden who led the new research. "Different parts of intelligence could be changing in lots of different ways." [Life's Extremes: Smart vs. Dumb]

Are you smarter than your grandma?

The world is full of evidence that modern humans have more going on upstairs than their ancestors did: Smartphones. Heart transplants. A basic understanding that germs cause diseases.

Beyond these technological advances, though, is another hint that humans are getting smarter. It's called the Flynn effect, named after intelligence researcher James Flynn, an emeritus professor of the University of Otago in New Zealand.

Since IQ, or intelligence quotient, tests have been revised and standardized several times in the past 100 years, to see the Flynn effect, scientists have their volunteers take tests designed for previous generations. Flynn and his colleagues have found that all around the world, the new generations score higher on the old tests than the original test takers did.

The increases are no small matter, either — they vary by geography, but tend to be around three extra IQ points per decade. [Creative Genius: The World's Greatest Minds]

Flynn and many other researchers suspect that rising IQ scores reflect improving modern environments. IQ is part heritable and part environmental enrich a young child's environment with opportunities to learn, and they'll have a higher IQ later in life. Better nutrition, more schooling and more stimulation could also explain the Flynn effect.

So could the kind of thinking that people do today. If you asked someone in the 19th century the relationship between a dog and a hare, they'd likely go with something concrete, based on their real-life experience with the two animals, Woodley said. "The dog hunts the hare" might be a typical response.

Today, people are taught to think more abstractly. A modern person would be more likely to say that both dogs and hares are mammals, for example.

"These sort of heuristics and modern habits of thought have changed the way people have approached answering IQ tests," Woodley said.

The dulling of humanity

Even as the Flynn effect sends IQ scores skyrocketing, some researchers argue a darker view. Humans aren't getting smarter, they say. They're getting stupider.

In November 2012, Stanford University School of Medicine researcher Gerald Crabtree published two papers in the journal Trends in Genetics suggesting that humanity's intelligence peaked between 2,000 and 6,000 years ago.

Crabtree based this assertion on genetics. About 2,000 to 5,000 genes control human intelligence, he estimated. At the rate at which genetic mutations accumulate, Crabtree calculated that within the last 3,000 years, all of humanity has sustained at least two mutations harmful to these intellect-determining genes (and will sustain a couple more in another 3,000 years). Not every mutation will cause harm — genes come in pairs, and some weaknesses caused by mutation can be covered for by the healthy half of the pair, Crabtree wrote but the calculation suggests that intelligence is more fragile than it seems.

Furthermore, he argued, intelligence isn't as evolutionarily important to humans today as it was when the species was hunter-gatherers. Thousands of years ago, failing to grasp the aerodynamics of throwing a spear when a lion was coming at you meant you were toast — no more passing along your genes to offspring. Modern man rarely faces such life-or-death tests of wits, Crabtree wrote. [10 Things That Make Humans Special]

Another theory holds that humanity's genetic capacity for intelligence is in decline because of a phenomenon called dysgenic mating. Since the mid-1800s, IQ and reproduction have been negatively correlated, studies have found. To put it bluntly, people who are more intelligent have fewer babies. Because intelligence is part genetic, some researchers argue that, if anything, IQs should be dropping.

Instead, scores are going up, creating a paradox for the dysgenic mating theory, Woodley said.

Understanding an intelligence paradox

Now, Woodley and his colleagues think they may have solved that paradox, and the news is not good.

To look back at historical intelligence, the researchers turned not to IQ tests, but to reaction time. Simple reaction time (the amount of time it takes to respond to a stimulus) is correlated with IQ, Woodley said, and not nearly as sensitive to cultural influences as IQ tests.

"The idea is that reaction times represent your ability to engage in very basic and elementary cognitive processing," he said. [The 10 Best Ways to Keep Your Mind Sharp]

In the 1880s, English scientist Sir Francis Galton measured reaction times in 2,522 young men and 888 young women from a wide variety of socioeconomic statuses. He found that men's average reaction time to a stimulus was 183 milliseconds, and women's was 187 ms. (Galton's reaction time studies were part of his work as the founder of the field of eugenics, the idea that only the "best" should reproduce. Eugenics was embraced by a variety of high-profile people in the early 1900s, most notably Adolf Hitler, who wanted to establish a "master race" of Aryans.)

Twelve similar studies to Galton's conducted after 1941, on the other hand, found an average reaction time for men of 250 ms and for women of 277 ms — markedly slower. A review study detailing those findings was published in The American Journal of Psychology in 2010.

Woodley and his colleagues expanded on the 2010 work, including additional data and matching the old and new studies to be sure they were measuring the same things. Despite the fact that timers have improved quite a bit since the 1880s, Woodley is confident that Galton's measurements are accurate. Galton used a pendulum-based machine to time reactions, and such machines are generally accurate within 10 ms, Woodley said.

Galton's data also behaves as you might expect it to behave if it were correct, Woodley said. For example, groups with more inbreeding performed worse on the reaction time test.

The new analysis was "crystal clear," Woodley said.

"We found a very, very robust trend with time, toward slowing speeds of reaction," he said, "which is consistent with the idea that the more stable, the more culturally neutral, the more genetically influenced components of intelligence have been declining rather than increasing."

What that suggests is that even as IQ scores rise with education and health, humanity's capacity to get smarter is shrinking. In essence, the Flynn effect might be hiding an underlying decline, a "psychometric dark matter" not visible on pen-and-paper intelligence tests, Woodley said.

"An analogy to use would be lower-quality seeds, but higher-quality fertilizers," he said, referring to this idea that a high-quality environment may be masking the decline in "smart" genes.

If true, the reasons are unknown. Possibilities range from exposure to neurotoxins in modern society to natural selection.

Smarter or dumber?

Not everyone sees the new reaction time findings as the final word, however.

"To sum up 100 years of research, there is a reliable correlation between measures of reaction time and measures of IQ, but the order of such correlations is far short of what would be required to use the former to explain the latter," said Theodore Nettelbeck, a psychologist at the University of Adelaide who researches intelligence.

In other words, Nettelbeck told LiveScience, using reaction time as a proxy for IQ leaves something to be desired. At best, he said, reaction times to complex stimuli might explain about 20 percent to 25 percent of the variation in IQs, and simple reaction times explain a lot less.

Nettelbeck also raised concerns about the various experiments analyzed in the new study and how comparable they might be.

"Not only would there be differences in the technologies for timing responses, which may or not influence the outcome measures there would also be procedural differences in the numbers of trials from which means [averages] have been derived, instructions to participants, extent of prior practice, the nature of stimuli, the form of response keys, all of which can influence the length of response," he said.

Reaction time can also be tricky to interpret, said James Flynn, for whom the Flynn effect is named.

"A dull person has just as quick a peak reaction time as a brilliant person," Flynn told LiveScience. The difference is that someone with a low IQ typically can't stay focused and so their reaction times won't be consistent throughout an experiment their scores vary more widely than those of high-IQ people.

"Is this really neural speed, or for a dull person, [or] is it much more difficult for them to be attentive to the task?" Flynn said.

Other factors play a role as well, he added. In studies of schoolchildren, kids in Hong Kong are quicker off the mark in reaction time tests than British kids. You could read those results to mean Chinese kids are smarter than Britons, Flynn said. Or perhaps Chinese kids are just more willing to take risks.

The good news is that even if Woodley and his colleagues are correct that the soil of the human mind is becoming less fertile, the species is not doomed to a slow decline into idiocy. Norway and Sweden are exceptions to the rule that less educated, lower-IQ people have more children, Flynn said. Both countries have few class differences and make birth control easily available. And with IQ scores still rising in most of the world, environment seems to be trumping possible genetic problems.

"Apparently, we haven't explored the limits of our genes yet," Flynn said.


What Does IQ Really Measure?

Kids who score higher on IQ tests will, on average, go on to do better in conventional measures of success in life: academic achievement, economic success, even greater health, and longevity. Is that because they are more intelligent? Not necessarily. New research concludes that IQ scores are partly a measure of how motivated a child is to do well on the test. And harnessing that motivation might be as important to later success as so-called native intelligence.

Researchers have long debated what IQ tests actually measure, and whether average differences in IQ scores--such as those between different ethnic groups--reflect differences in intelligence, social and economic factors, or both. The debate moved heavily into the public arena with the 1994 publication of The Bell Curve by Richard Herrnstein and Charles Murray, which suggested that the lower average IQ scores of some ethnic groups, such as African-Americans and Hispanics, were due in large part to genetic differences between them and Caucasian groups. That view has been challenged by many scientists. For example, in his 2009 book "Intelligence and How to Get It," Richard Nisbett, a psychologist at the University of Michigan, Ann Arbor, argued that differences in IQ scores largely disappear when researchers control for social and economic factors.

New work, led by Angela Lee Duckworth, a psychologist at the University of Pennsylvania, and reported online today in the Proceedings of the National Academy of Sciences explores the effect of motivation on how well people perform on IQ tests. While subjects taking such tests are usually instructed to try as hard as they can, previous research has shown that not everyone makes the maximum effort. A number of studies have found that subjects who are promised monetary rewards for doing well on IQ and other cognitive tests score significantly higher.

To further examine the role of motivation on both IQ test scores and the ability of IQ tests to predict life success, Duckworth and her team carried out two studies, both reported in today's paper. First, they conducted a "meta-analysis" that combined the results of 46 previous studies of the effect of monetary incentives on IQ scores, representing a total of more than 2000 test-taking subjects. The financial rewards ranged from less than $1 to $10 or more. The team calculated a statistical parameter called Hedge's g to indicate how big an effect the incentives had on IQ scores g values of less than 0.2 are considered small, 0.5 are moderate, and 0.7 or higher are large.

Duckworth's team found that the average effect was 0.64 (which is equivalent to nearly 10 points on the IQ scale of 100), and remained higher than 0.5 even when three studies with unusually high g values were thrown out. Moreover, the effect of financial rewards on IQ scores increased dramatically the higher the reward: Thus rewards higher than $10 produced g values of more than 1.6 (roughly equivalent to more than 20 IQ points), whereas rewards of less than $1 were only one-tenth as effective.

In the second study, Duckworth and her colleagues analyzed data from an earlier study of more than 500 boys from Pittsburgh, Pennsylvania, whose IQs were tested in the late 1980s by a team from the University of Wisconsin, Madison. During the IQ test, the boys, whose average age was 12.5 years, were videotaped then observers trained to detect signs of boredom and lack of motivation (such as yawning, laying their heads on the table, or looking often around the room) viewed the videos and assigned motivation scores.

Researchers followed the boys over time, and when the boys reached early adulthood (average age 24), 251 of them agreed to a series of interviews about their educational and job achievements (there were no differences in IQ or other key factors between those boys who participated and those who didn't.)

Duckworth's team analyzed the results of these earlier studies to see what they said about the relationship between motivation, IQ scores, and life success. By constructing a series of computer models of the data, the team found that higher motivation accounted for a significant amount of the differences in IQ scores and also in how well IQ predicted later success in life. For example, differences in motivation levels accounted for up to 84% of the differences between the boys in how many years of school they had completed or whether they had been able to find a job. On the other hand, motivation differences accounted for about only 25% of the differences in how well they had done in school as teenagers. According to the researchers, that suggests that native intelligence does still play an important role in both IQ scores and academic achievement.

Nevertheless, the Duckworth team concludes that IQ tests are measuring much more than just raw intelligence--they also measure how badly subjects want to succeed both on the test and later in life. Yet Duckworth and her colleagues caution that motivation isn't everything: The lower role for motivation in academic achievement, they write, suggests that "earning a high IQ score requires high intelligence in addition to high motivation."

The study has important social policy implications, Duckworth says. "I hope that social scientists, educators, and policy makers turn a more critical eye to any kind of measure, intelligence or otherwise," she says, adding that how hard people try "could be as important to success in life as intellectual ability itself." Duckworth suggests that admissions to programs for "gifted and talented" children should not be based on IQ scores alone, but also on "who wants to do the work."

Nisbett agrees that the study is "tremendously important in its implications." Motivation, along with self-discipline, "are crucial," Nisbett says. "A high IQ and a subway token will only get you into town."

Lex Borghans, an economist at the Maastricht University in the Netherlands, who has also studied the relationship between intelligence tests and economic success, says the new report shows that "both intelligence and personality matter." Even if native intelligence cannot be increased, Borghans says, "there might be other routes to success."


Ways to Inflate Your IQ

Many people think of IQ as a genetic trait, like brown eyes or short legs: You're born with it and you're stuck with it. Now, a growing body of research is showing that a person's IQ can rise—and even fall—over the years.

Scores can change gradually or quickly, after as little as a few weeks of cognitive training, research shows. The increases are usually so incremental that they're not immediately perceptible to individuals, and the intelligence-boosting effects of cognitive training can fade after a few months.

In the latest study, 33 British students were given IQ tests and brain scans at ages 12 to 16 and again about four years later by researchers at the Wellcome Trust Centre for Neuroimaging at University College London 9% of the students showed a significant change of 15 points or more in IQ scores.

On a scale where 90 to 110 is considered average, one student's IQ rose 21 points to 128 from 107, lifting the student from the 68th percentile to the 97th compared with others the same age, says Cathy Price, professor of cognitive neuroscience at the center and co-author of the study, published last month in Nature. Another student's score skidded out of the "high average" category, to 96 from 114.

Swings in individual IQ scores are often written off as the product of measurement error or a test subject having a bad day. But MRIs in this study showed changes in gray matter in areas corresponding to fluctuations in the kids' skills, Dr. Price says. Although the sample size is small, the study drew wide attention because it is among the first to show how changes in IQ scores may be reflected in actual shifts in brain structure.

Testing Cognitive Skills

Pre-employment tests measure some cognitive abilities that are similar to those gauged by IQ tests and are used for selecting employees for many kinds of jobs. Try some sample questions.

Take the Test

Try some sample questions from various IQ tests.

"There are many myths about IQ, such as the notion that IQ is a fixed number or that it is a crystal ball for future performance," says Eric Rossen, director of professional development and standards for the National Association of School Psychologists in Bethesda, Md.

The first reliable tests of intelligence in the U.S. were published in the early 1900s, says Alan S. Kaufman, clinical professor of psychology at Yale University and co-author of several IQ tests. Scores compare people to others of the same age based on a wide range of cognitive questions and tasks, from processing information and analyzing patterns, to solving age-appropriate math problems and recalling facts or vocabulary. A score in the 90 to 110 range is considered average. A "genius" may score 140 and above, he says.

IQ tests have been a target of ongoing criticism. Their use led to the misclassification of many children as "intellectually disabled" in the 1970s and 1980s. Similar cognitive tests used by employers to screen recruits have been attacked as discriminatory against African-American and Hispanic job candidates.

Today in schools, individual IQ-type tests are limited mainly to helping plan instruction for some children with specific learning disabilities and helping identify students for gifted programs. Kathleen Lundquist, president of APTMetrics, a Darien, Conn., human-resources consulting firm, says cognitive tests in the workplace today are often revised to eliminate adverse effects on minorities and are most often used as a screening tool for entry-level jobs.

There are practical steps people can take to see longer-term IQ changes. A 30-year study at the National Institute of Mental Health found that people whose work involves complex relationships, setting up elaborate systems or dealing with people or difficult problems, tend to perform better over time on cognitive tests. Test scores of people whose jobs are simple and require little thought actually tend to decline, according to the research, published in 1999 in Psychology and Aging.

New tasks stimulate the brain most. When researchers at the University of Hamburg subjected 20 young adults to one month of intense training in juggling, they found an increase in the corresponding gray matter in the brain as early as seven days after the training began. The added gray matter receded when the training was stopped, although the participants were still able to juggle, says the study, published in 2008 in PLoS One.

IQ tests don't measure such abilities as creativity, common sense or social sensitivity. They do assess many kinds of knowledge and abilities, including abstract reasoning skills. Rising scores in abstract reasoning are the main reason average IQ scores have been increasing by about three points every decade since the 1930s, based on studies by James Flynn, a professor emeritus of political studies at the University of Otago in New Zealand. That may be partly because children spend nearly twice as many years in school, on average, than children decades ago, says Wendy M. Williams, a professor in the department of human development at Cornell University.

Fluctuations in IQ scores over time underscore the brain-boosting benefits of a complex job, musical training, advanced schooling and new experiences throughout a lifetime.

Work & Family Mailbox

Schooling in general raises IQ by several points a year, based on research by Stephen Ceci, a professor of developmental psychology at Cornell, and others. "If you look at an IQ test, it asks things like, 'Who wrote Hamlet?' or 'Why do we pay for postage?' You are most likely to come across the answers in school," Dr. Ceci says. Even nonverbal abilities such as solving puzzles and spatial tasks may blossom because math classes today include visual reasoning with matrices, mazes, blocks or designs, he adds.

Intense training can raise scores. Using a method called "n-back," researchers at the University of Michigan had young adults practice recalling letter sequences by flashing a series of letters on a screen and asking them to press a key whenever they saw the same letter that appeared "n" times earlier, such as one or two times.

Training for about 25 minutes a day for eight to 19 days was linked to higher scores on tests of fluid intelligence, with gains increasing with the duration of the training, says Susanne Jaeggi, co-author of the study, published in 2008 in Proceeding of the National Academy of Sciences.

The gains tend to fade after practice stops, based on studies of children, Dr. Jaeggi says. "You need some booster sessions" to maintain improvements, she says. Other research has found training people to switch mental tasks quickly also can lift scores.

Music lessons are linked to higher IQ throughout life, according to research by E. Glenn Schellenberg, a psychology professor at the University of Toronto at Mississauga. Six years' lessons lifted children's IQ scores an average 7.5 points those gains eroded to two points by college age, says a study published in 2006 in the Journal of Educational Psychology.

In a study this year, researchers at the University of Kansas found practicing musicians who are active for a decade or more continue to post higher IQs beyond age 60.

Write to Sue Shellenbarger at [email protected]

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7.5 Measures of Intelligence

While you’re likely familiar with the term “IQ” and associate it with the idea of intelligence, what does IQ really mean? IQ stands for intelligence quotient and describes a score earned on a test designed to measure intelligence. You’ve already learned that there are many ways psychologists describe intelligence (or more aptly, intelligences). Similarly, IQ tests—the tools designed to measure intelligence—have been the subject of debate throughout their development and use.

When might an IQ test be used? What do we learn from the results, and how might people use this information? While there are certainly many benefits to intelligence testing, it is important to also note the limitations and controversies surrounding these tests. For example, IQ tests have sometimes been used as arguments in support of insidious purposes, such as the eugenics movement (Severson, 2011). The infamous Supreme Court Case, Buck v. Bell, legalized the forced sterilization of some people deemed “feeble-minded” through this type of testing, resulting in about 65,000 sterilizations (Buck v. Bell, 274 U.S. 200 Ko, 2016). Today, only professionals trained in psychology can administer IQ tests, and the purchase of most tests requires an advanced degree in psychology. Other professionals in the field, such as social workers and psychiatrists, cannot administer IQ tests. In this section, we will explore what intelligence tests measure, how they are scored, and how they were developed.

Measuring Intelligence

It seems that the human understanding of intelligence is somewhat limited when we focus on traditional or academic-type intelligence. How then, can intelligence be measured? And when we measure intelligence, how do we ensure that we capture what we’re really trying to measure (in other words, that IQ tests function as valid measures of intelligence)? In the following paragraphs, we will explore the how intelligence tests were developed and the history of their use.

The IQ test has been synonymous with intelligence for over a century. In the late 1800s, Sir Francis Galton developed the first broad test of intelligence (Flanagan & Kaufman, 2004). Although he was not a psychologist, his contributions to the concepts of intelligence testing are still felt today (Gordon, 1995). Reliable intelligence testing (you may recall from earlier chapters that reliability refers to a test’s ability to produce consistent results) began in earnest during the early 1900s with a researcher named Alfred Binet (Figure 7.13). Binet was asked by the French government to develop an intelligence test to use on children to determine which ones might have difficulty in school it included many verbally based tasks. American researchers soon realized the value of such testing. Louis Terman, a Stanford professor, modified Binet’s work by standardizing the administration of the test and tested thousands of different-aged children to establish an average score for each age. As a result, the test was normed and standardized, which means that the test was administered consistently to a large enough representative sample of the population that the range of scores resulted in a bell curve (bell curves will be discussed later). Standardization means that the manner of administration, scoring, and interpretation of results is consistent. Norming involves giving a test to a large population so data can be collected comparing groups, such as age groups. The resulting data provide norms, or referential scores, by which to interpret future scores. Norms are not expectations of what a given group should know but a demonstration of what that group does know. Norming and standardizing the test ensures that new scores are reliable. This new version of the test was called the Stanford-Binet Intelligence Scale (Terman, 1916). Remarkably, an updated version of this test is still widely used today.

In 1939, David Wechsler, a psychologist who spent part of his career working with World War I veterans, developed a new IQ test in the United States. Wechsler combined several subtests from other intelligence tests used between 1880 and World War I. These subtests tapped into a variety of verbal and nonverbal skills, because Wechsler believed that intelligence encompassed “the global capacity of a person to act purposefully, to think rationally, and to deal effectively with his environment” (Wechsler, 1958, p. 7). He named the test the Wechsler-Bellevue Intelligence Scale (Wechsler, 1981). This combination of subtests became one of the most extensively used intelligence tests in the history of psychology. Although its name was later changed to the Wechsler Adult Intelligence Scale (WAIS) and has been revised several times, the aims of the test remain virtually unchanged since its inception (Boake, 2002). Today, there are three intelligence tests credited to Wechsler, the Wechsler Adult Intelligence Scale-fourth edition (WAIS-IV), the Wechsler Intelligence Scale for Children (WISC-V), and the Wechsler Preschool and Primary Scale of Intelligence—IV (WPPSI-IV) (Wechsler, 2012). These tests are used widely in schools and communities throughout the United States, and they are periodically normed and standardized as a means of recalibration. As a part of the recalibration process, the WISC-V was given to thousands of children across the country, and children taking the test today are compared with their same-age peers (Figure 7.13).

The WISC-V is composed of 14 subtests, which comprise five indices, which then render an IQ score. The five indices are Verbal Comprehension, Visual Spatial, Fluid Reasoning, Working Memory, and Processing Speed. When the test is complete, individuals receive a score for each of the five indices and a Full Scale IQ score. The method of scoring reflects the understanding that intelligence is comprised of multiple abilities in several cognitive realms and focuses on the mental processes that the child used to arrive at his or her answers to each test item.

Interestingly, the periodic recalibrations have led to an interesting observation known as the Flynn effect. Named after James Flynn, who was among the first to describe this trend, the Flynn effect refers to the observation that each generation has a significantly higher IQ than the last. Flynn himself argues, however, that increased IQ scores do not necessarily mean that younger generations are more intelligent per se (Flynn, Shaughnessy, & Fulgham, 2012).

Ultimately, we are still left with the question of how valid intelligence tests are. Certainly, the most modern versions of these tests tap into more than verbal competencies, yet the specific skills that should be assessed in IQ testing, the degree to which any test can truly measure an individual’s intelligence, and the use of the results of IQ tests are still issues of debate (Gresham & Witt, 1997 Flynn, Shaughnessy, & Fulgham, 2012 Richardson, 2002 Schlinger, 2003).

What Do You Think?

Capital Punishment and Criminals with Intellectual Disabilities

The case of Atkins v. Virginia was a landmark case in the United States Supreme Court. On August 16, 1996, two men, Daryl Atkins and William Jones, robbed, kidnapped, and then shot and killed Eric Nesbitt, a local airman from the U.S. Air Force. A clinical psychologist evaluated Atkins and testified at the trial that Atkins had an IQ of 59. The mean IQ score is 100. The psychologist concluded that Atkins was “mildly mentally retarded.”

The jury found Atkins guilty, and he was sentenced to death. Atkins and his attorneys appealed to the Supreme Court. In June 2002, the Supreme Court reversed a previous decision and ruled that executions of intellectually disabled criminals are ‘cruel and unusual punishments’ prohibited by the Eighth Amendment. The court wrote in their decision:

Clinical definitions of mental retardation require not only subaverage intellectual functioning, but also significant limitations in adaptive skills. Mentally retarded persons frequently know the difference between right and wrong and are competent to stand trial. Because of their impairments, however, by definition they have diminished capacities to understand and process information, to communicate, to abstract from mistakes and learn from experience, to engage in logical reasoning, to control impulses, and to understand others’ reactions. Their deficiencies do not warrant an exemption from criminal sanctions, but diminish their personal culpability (Atkins v. Virginia, 2002, par. 5).

The court also decided that there was a state legislature consensus against the execution of the intellectually disabled people and that this consensus should stand for all of the states. The Supreme Court ruling left it up to the states to determine their own definitions of mental retardation, a widely used term at the time, and intellectual disability. The definitions vary among states as to who can be executed. In the Atkins case, a jury decided that because he had many contacts with his lawyers and thus was provided with intellectual stimulation, his IQ had reportedly increased, and he was now smart enough to be executed. He was given an execution date and then received a stay of execution after it was revealed that lawyers for co-defendant, William Jones, coached Jones to “produce a testimony against Mr. Atkins that did match the evidence” (Liptak, 2008). After the revelation of this misconduct, Atkins was re-sentenced to life imprisonment.

Atkins v. Virginia (2002) highlights several issues regarding society’s beliefs around intelligence. In the Atkins case, the Supreme Court decided that intellectual disability does affect decision making and therefore should affect the nature of the punishment such criminals receive. Where, however, should the lines of intellectual disability be drawn? In May 2014, the Supreme Court ruled in a related case (Hall v. Florida) that IQ scores cannot be used as a final determination of a prisoner’s eligibility for the death penalty (Roberts, 2014).

The Bell Curve

The results of intelligence tests follow the bell curve, a graph in the general shape of a bell. When the bell curve is used in psychological testing, the graph demonstrates a normal distribution of a trait, in this case, intelligence, in the human population. Many human traits naturally follow the bell curve. For example, if you lined up all your female schoolmates according to height, it is likely that a large cluster of them would be the average height for an American woman: 5’4”–5’6”. This cluster would fall in the center of the bell curve, representing the average height for American women (Figure 7.14). There would be fewer women who stand closer to 4’11”. The same would be true for women of above-average height: those who stand closer to 5’11”. The trick to finding a bell curve in nature is to use a large sample size. Without a large sample size, it is less likely that the bell curve will represent the wider population. A representative sample is a subset of the population that accurately represents the general population. If, for example, you measured the height of the women in your classroom only, you might not actually have a representative sample. Perhaps the women’s basketball team wanted to take this course together, and they are all in your class. Because basketball players tend to be taller than average, the women in your class may not be a good representative sample of the population of American women. But if your sample included all the women at your school, it is likely that their heights would form a natural bell curve.

The same principles apply to intelligence tests scores. Individuals earn a score called an intelligence quotient (IQ). Over the years, different types of IQ tests have evolved, but the way scores are interpreted remains the same. On most IQ tests, the average (or mean) IQ score is 100. Standard deviations describe how data are dispersed in a population and give context to large data sets. The bell curve uses the standard deviation to show how all scores are dispersed from the average score (Figure 7.15). In modern IQ testing, one standard deviation is 15 points. So a score of 85 would be described as “one standard deviation below the mean.” How would you describe a score of 115 and a score of 70? Any IQ score that falls within one standard deviation above and below the mean (between 85 and 115) is considered average, and 68% of the population has IQ scores in this range. An IQ score of 130 or above is considered a superior level.

Only 2.2% of the population has an IQ score below 70 (American Psychiatric Association [APA], 2013). If a person earns a score approximately two standard deviations below the mean on an intelligence test, (about 70 on a test with a mean of 100), has major deficits in adaptive functioning, and these cognitive and adaptive deficits were present before the age of 18, they could be diagnosed as having an intellectual disability (ID). Formerly known as mental retardation, the accepted term now is intellectual disability, and it has four subtypes: mild, moderate, severe, and profound (Table 7.4). The Diagnostic and Statistical Manual of Psychological Disorders lists criteria for each subgroup (APA, 2013).

Intellectual Disability Subtype Percentage of Population with Intellectual Disabilities Description
Mild 85% 3rd- to 6th-grade skill level in reading, writing, and math may be employed and live independently
Moderate 10% Basic reading and writing skills functional self-care skills requires some oversight
Severe 5% Functional self-care skills requires oversight of daily environment and activities
Profound <1% May be able to communicate verbally or nonverbally requires intensive oversight

On the other end of the intelligence spectrum are those individuals whose IQs fall into the highest ranges. Consistent with the bell curve, about 2% of the population falls into this category. People are considered gifted if they have an IQ score of 130 or higher, or superior intelligence in a particular area. Long ago, popular belief suggested that people of high intelligence were maladjusted. This idea was disproven through a groundbreaking study of gifted children. In 1921, Lewis Terman began a longitudinal study of over 1500 children with IQs over 135 (Terman, 1925). His findings showed that these children became well-educated, successful adults who were, in fact, well-adjusted (Terman & Oden, 1947). Additionally, Terman’s study showed that the subjects were above average in physical build and attractiveness, dispelling an earlier popular notion that highly intelligent people were “weaklings.” Some people with very high IQs elect to join Mensa, an organization dedicated to identifying, researching, and fostering intelligence. Members must have an IQ score in the top 2% of the population, and they may be required to pass other exams in their application to join the group.

Dig Deeper

What’s in a Name? Mental Retardation

In the past, individuals with IQ scores below 70 and significant adaptive and social functioning delays were diagnosed with mental retardation. When this diagnosis was first named, the title held no social stigma. In time, however, the degrading word “retard” sprang from this diagnostic term. “Retard” was frequently used as a taunt, especially among young people, until the words “mentally retarded” and “retard” became an insult. As such, the DSM-5 now labels this diagnosis as “intellectual disability.” Many states once had a Department of Mental Retardation to serve those diagnosed with such cognitive delays, but most have changed their name to Department of Developmental Disabilities or something similar in language. The Social Security Administration still uses the term “mental retardation” but is considering eliminating it from its programming (Goad, 2013). Earlier in the chapter, we discussed how language affects how we think. Do you think changing the title of this department has any impact on how people regard those with developmental disabilities? Does a different name give people more dignity, and if so, how? Does it change the expectations for those with developmental or cognitive disabilities? Why or why not?

Why Measure Intelligence?

The value of IQ testing is most evident in educational or clinical settings. Children who seem to be experiencing learning difficulties or severe behavioral problems can be tested to ascertain whether the child’s difficulties can be partly attributed to an IQ score that is significantly different from the mean for her age group. Without IQ testing—or another measure of intelligence—children and adults needing extra support might not be identified effectively. In addition, IQ testing is used in courts to determine whether a defendant has special or extenuating circumstances that preclude him from participating in some way in a trial. People also use IQ testing results to seek disability benefits from the Social Security Administration.

The following case study demonstrates the usefulness and benefits of IQ testing. Candace, a 14-year-old girl experiencing problems at school in Connecticut, was referred for a court-ordered psychological evaluation. She was in regular education classes in ninth grade and was failing every subject. Candace had never been a stellar student but had always been passed to the next grade. Frequently, she would curse at any of her teachers who called on her in class. She also got into fights with other students and occasionally shoplifted. When she arrived for the evaluation, Candace immediately said that she hated everything about school, including the teachers, the rest of the staff, the building, and the homework. Her parents stated that they felt their daughter was picked on, because she was of a different race than the teachers and most of the other students. When asked why she cursed at her teachers, Candace replied, “They only call on me when I don’t know the answer. I don’t want to say, ‘I don’t know’ all of the time and look like an idiot in front of my friends. The teachers embarrass me.” She was given a battery of tests, including an IQ test. Her score on the IQ test was 68. What does Candace’s score say about her ability to excel or even succeed in regular education classes without assistance? Why were her difficulties never noticed or addressed?


Does A High IQ Guarantee Success? Maybe Not

The Intelligence Quotient (IQ) doesn&rsquot measure what we know it measures what we are able to understand. An IQ test consists of a series of exams aimed at assessing how well we reason, process information, and solve problems relative to other people our age. Anyone scoring within 10 points of 100 is said to be of average intelligence, which makes someone who scores a 130 the smartest person in the room. That is, unless they&rsquore in a room with some certifiable genius types such as Einstein, Da Vinci, Plato, or Ivan Drago (aka Rocky Balboa&rsquos rival), who all have an IQ over 160. But even those with the gift of genius aren&rsquot handed a guarantee &mdash success, like batteries, is sold separately.

Smart from the Start &ndash Why it Matters

Since studying is unlikely to boost our IQ, being born with genius in our genes is kind of like hitting the intelligence lottery. Although it is possible to boost cognitive ability by learning new skills and playing problem-solving games, these changes are unlikely to increase overall IQ (sorry, Sudoku lovers). In this way, IQ is like physical health: We can exercise our brain and muscles to help them grow, but the changes aren&rsquot permanent the moment we stop exercising, our brains and muscles start to return to their original form Individual differences in working memory within a nomological network of cognitive and perceptual speed abilities. Ackerman PL, Beier ME, Boyle MO. School of Psychology, Georgia Institute of Technology. Journal of Experimental Psychology. 2002 Dec 131(4):567-89 .

If we assume we&rsquore all racing towards some version of &ldquosuccess,&rdquo a high IQ is one heck of a head start. But that doesn&rsquot mean we should give up just because our number falls a little lower on the scale. The first runner out of the blocks doesn&rsquot always win the race, and having the highest IQ in the crowd doesn&rsquot guarantee success. That&rsquos because there are some things an IQ test can&rsquot measure. For starters, there&rsquos no Street Smarts section on an IQ test, meaning a degree from the school of hard knocks doesn&rsquot carry much weight. Testing our reasoning also overlooks the various ways we learn: Some people can read and retain information while others need to get hands-on, and so on. One method isn&rsquot necessarily &ldquosmarter&rdquo than another they&rsquore just different.

IQ also overlooks what researcher Howard Gardner refers to as &ldquomultiple intelligences,&rdquo or the human capacity to possess a range of traits and abilities &mdash not all of which can be measured via testing. Similarly, the IQ test fails to measure traits such as creativity, imagination and innovation, all of which can contribute to a person&rsquos success (or lack thereof) The use of imagery by intelligent and by creative schoolchildren. Shaw GA. Journal of General Psychology. 1985 Apr 112(2):153-71 .

What iq can do for you &mdash and what it can&rsquot

Despite flaws in IQ testing, intelligence has been shown to play a role in determining achievement, business success, and even the rate of our mortality &mdash mostly because IQ strongly correlates with income Longitudinal cohort study of childhood IQ and survival up to age 76. Lawrence J Whalley, Ian J Deary. Department of Mental Health, University of Aberdeen. British Medical Journal. 2001 Jan . Having a high IQ also increases the likelihood of becoming a high-performer in a variety of aptitudes, from science to music. That&rsquos because a genius can process, store, and recall an absurd amount of highly complex information &mdash it&rsquos called working memory capacity The relationship between working memory capacity and executive functioning: evidence for a common executive attention construct. McCabe DP, Roediger HL, McDaniel MA, Balota DA, Hambrick DZ. Department of Psychology, Colorado State University. Neuropsychology. 2010 Mar 24(2):222-43 The generality of working memory capacity: a latent-variable approach to verbal and visuospatial memory span and reasoning. Kane MJ, Hambrick DZ, Tuholski SW, Wilhelm O, Payne TW, Engle RW. Department of Psychology, University of North Carolina at Greensboro. Journal of Experimental Psychology. 2004 Jun 133(2):189-217 .

But if being a brainiac was the one and only criterion for success, everyone with a lofty IQ would be wildly successful &mdash and obviously, that&rsquos not always the case. Even a genius can squander their intelligence jackpot Cognitive sophistication does not attenuate the bias blind spot. West RF, Meserve RJ, Stanovich KE. Department of Graduate Psychology, James Madison University. Journal of Personality and Social Psychology. 2012 Sep 103(3):506-19 . When smart people encounter a problem that needs solving, they tend to forgo facts in favor of mental shortcuts. Trouble is, these shortcuts can lead to foolish mistakes and ultimately the wrong answer. Turns out Mom was right: We can be too smart for our own good.

So if great intellect doesn&rsquot guarantee success, what factors separate an average Joe from a highly intelligent outlier? The real question becomes: Can we actually compete with genius by going from good to great?

The Genius Myth &mdash The Answer/Debate

Genius is real, but it can also be really misleading. For one thing, putting too much stake in &ldquogenius&rdquo implies the entire average-achieving population is virtually helpless. When taken at face value, the idea of innate intelligence plays into the genius myth. This legend would have us mere mortals believe that we either have it or we don&rsquot &mdash whatever &ldquoit&rdquo is. But when the curtain is pulled back, we see that genius is nothing more than a comforting parable. It comes in handy when trying to explain why some people seem to have it all, but it doesn&rsquot accurately depict the full scope and scale of human intelligence.

In reality, success is based on a whole lot more than genius alone. Persistence, practice, socio-emotional skills, our environment, the way we&rsquore raised, and luck all combine to determine what we will achieve Beyond IQ: broad-based measurement of individual success potential or &ldquoemotional intelligence&rdquo. Mehrabian A. Department of Psychology, University of California. Genetic, Social and General Psychology Monographs. 2000 May 126(2):133-239 . This explains why early interventions in child development so often improve individuals&rsquo chances of success &mdash our potential isn&rsquot fixed the day we&rsquore born rather, it&rsquos highly fluid and dependent on a number of both external and internal factors.

One of these factors &mdash grit &mdash has been shown to play a particularly big role when it comes to success. Grit is best defined as the perseverance and passion for a long-term goal. It&rsquos a single-minded focus that allows us to persist well beyond the point at which others would give up. One study found that West Point cadets and spelling bee superstars linked this grit factor with success time after time Grit: perseverance and passion for long-term goals. Duckworth AL, Peterson C, Matthews MD, Kelly DR. Department of Psychology, University of Pennsylvania. Journal of Personality and Social Psychology. 2007 Jun 92 (6):1087-101 . The soldiers and spellers who were most successful were more determined, had greater willpower, and exhibited better self-control than their lower-achieving peers. Researchers found that the smarter kids just didn&rsquot try as hard or want it as bad as the gritty kids Grit: perseverance and passion for long-term goals. Duckworth AL, Peterson C, Matthews MD, Kelly DR. Department of Psychology, University of Pennsylvania. Journal of Personality and Social Psychology. 2007 Jun 92 (6):1087-101 Role of test motivation in intelligence testing. Angela Lee Duckworth, Patrick D. Quinn, Donald R. Lynam, Rolf Loeber, and Magda Stouthamer-Loeberd. Department of Psychology, University of Pennsylvania. Psychological and Cognitive Sciences. 2011 April 25 . Grit and IQ are only weakly associated with each other, so a person doesn&rsquot need to be a genius to be gritty as all get out. I guess we could say it&rsquos better to be average and hardworking than to be a lazy genius.

Smart Versus Successful &mdash The Takeaway

When it comes determining to success, IQ isn&rsquot a promise, it&rsquos more of a performance enhancer. If genius is the elevator to the top, we&rsquoll just have to take the stairs. It may take longer, but it&rsquoll still get us to where we want to go.

Do you believe that a high IQ guarantees success? Share in the comments below!