Chapter 8. Higher order cognition: Language and Intelligence

8.7. Genes, Environment, and IQ scores

Let us briefly review some of the more recent scientific studies about genes and IQ scores. Genetic factors do play some role in the determination of IQ scores, but these are hard to separate from environmental ones. For example, biological sex is genetically determined, and for centuries, patriarchal societies, like the United States, have regarded females as intellectually inferior to males. Despite the fact that many eugenicists were married men, their wives, who were White middle-class women, were also harmed by eugenicist claims that they lacked intelligence and were only fit for child-rearing, and home-making (Yakushko, 2019). However, there is no scientific evidence to support that males are intellectually superior to females. In fact, there are very few innate sex differences in cognitive aptitudes. Historically, females have been shown to do better on verbal tasks than males, whereas males do better on math tests, but these differences are largely environmental (Grose-Fifer & diFilipo, 2017). Boys and girls are frequently treated differently at home, in school, and by society in general. For example, children are often given gender-specific toys to play with and are encouraged to engage in behaviors that are perceived to be gender-specific. They are also discouraged from behaving in ways that are not considered gender-consistent. Can you think of how the toys that you were given and the games that you were encouraged to play as a child might have shaped your cognitive abilities as a young adult?

Race is not Biological

It is also important for us to highlight again in this chapter, that in contrast to sex, race is not a biological construct. In other words, you cannot tell a person’s race from looking at their genes (Berry et al., 2014; Guthrie, 1998; Nisbett et al, 2012). This is a long-perpetuated myth. Race is NOT based on genes, it is socially constructed—people decide who belongs to one race or another, based on skin color, hair texture, and the shape of facial features. People within a single family share a lot of common genes, but often vary widely in their physical characteristics. People show more genetic variation within a race than across races. Therefore, racial differences in IQ are NOT genetically determined. However, a person’s race affects how they are treated in society and often determines the socioeconomic opportunities they receive (Weiss & Saklofske, 2020).

Environmental influences including SES, neighborhood, family structure, schooling, parents’ level of education, nutrition, language, and culture, all affect IQ scores (Berry et al., 2014; Guthrie, 1998; Helms, 2012; Nisbett et al., 2012; Weiss & Saklofske, 2020). SES is a particularly important predictor of IQ (Weiss & Saklofske, 2020). Families with higher incomes generally have higher IQs (Berry et al., 2014). Importantly, individual IQ scores (and other measures of intelligence) can increase with environmental improvements. Infants and young children in poverty who attend Head Start programs do much better on IQ tests (and in school) than those who do not attend (Bauer, 2019). Furthermore, students, regardless of race, in well-resourced schools do better on IQ tests than those in poorly funded schools (Guthrie, 1998).

ACADEMIC Activists Fight Against Intelligence Testing.

For many years, eugenicists used IQ testing to justify the oppression of women, immigrants, and people of color. However, during the late 1920s, voices of dissent began to emerge (Guthrie, 1998). Academic activists began to conduct scientific programs of research that revealed the prejudicial nature of previous reports on IQ. Many of the scientists that contributed to this research were people of color and/or women.

Some of the first women to earn PhDs in psychology spent their academic careers conducting research showing that gender did not influence intelligence. In 1900, Helen Thompson Woolley was awarded a PhD from the University of Chicago. Her doctoral research showed that men and women performed similarly on IQ tests (Rodkey, 2010). Thompson Woolley spent her academic career showing that education affected IQ scores. Leta S. Hollingworth was awarded a PhD from Columbia University in 1916. Her doctoral research refuted the popular belief that women’s decision making abilities were affected by menstruation. Hollingworth’s research was even more remarkable, given that her mentor, Edward Thorndike, held the opposite view. However, like many psychologists of her time, Hollingworth believed that intelligence was inherited and she also endorsed eugenicist views (Benjamin 1990; Leta Stetter Hollingworth, 2023).

In 1927, Horace Mann Bond (Figure 8.6), a young Black sociology professor at Langston University, Oklahoma, reported that IQ testing conditions disadvantaged Black children. He showed that White psychologists took time to build rapport with White, but not Black children, which artificially depressed the IQ scores of Black children (Guthrie, 1998). Bond also demonstrated that low IQ scores among Black children were linked to environmental factors, like education and socioeconomic status (SES). He showed that many Black children from middle and upper-middle class families had IQ scores in the exceptional range (Guthrie, 1998). Bond spent his career working against segregation and later became the president of Lincoln University.

Photo of Horace Mann Bond
Figure 8.6. Horace Mann Bond

George Sanchez was an American educational psychologist of Mexican descent who demonstrated that Indigenous children and Chicano (Mexican-American) children were disadvantaged by IQ tests in similar ways to Black children. Low IQ scores in BIPOC children were used as justification for them to be educated in segregated, poorly resourced schools (Guthrie, 1998). In 1932, George Sanchez, took advantage of his position as Director of the Information and Statistics Division of the New Mexico State Department of Education to speak out against the inadequacies of the tests that were being used to assess the intelligence of Chicano children, many of whom spoke Spanish and lived in poverty (Tevis, 2020; Guthrie, 1998). Although IQ tests were translated into Spanish, the translations were poor and reflected the cultural values of White middle-class Americans (Guthrie, 1998). Sanchez later became a professor at the University of Texas, and remained an academic activist throughout his life. He continued to protest and testify against racist policies, and advocated for better education for children from marginalized groups, especially Chicano children (Tevis, 2020).

In 1935, Otto Klineberg, a Canadian psychologist, drew attention to the cultural inappropriateness of intelligence testing of indigenous children, pointing out that children of the Dakota nation were used to cooperating rather than competing. Often they did not answer the psychologists’ questions unless they felt sure that their peers also knew the answer (Guthrie, 1998). This was an important insight, because when children refused to answer the questions on the intelligence tests, White psychologists interpreted their silence as a lack of intelligence.

In the 1930s, as more Black students were admitted to graduate schools, many focused their graduate school research on demonstrating that Black people were in no way less intelligent than Whites (Guthrie, 1998). For example, in 1935, Herman Canady’s thesis for his Masters’ degree followed Horace Mann Bond’s lead by showing that Black children scored higher when the Stanford-Binet scale was administered by Black psychologists compared to White psychologists (Guthrie, 1998). However, it was not until 1979, that a team of Black psychologists and civil rights lawyers brought the issue to federal court in California. The state of California then ruled that intelligence tests – like the Stanford Binet, were racially and culturally biased, and banned their use for Black children. This helped to reduce the high number of Black students who were being misdirected into special education classes on the basis of their scores (Guthrie, 1998). Improved versions of the Stanford-Binet and other intelligence tests are still widely used today in many other US States (Gibbons & Warne, 2019) and Black children are still being inappropriately placed in special education at unjustifiably high rates (US Department of Education, 2016). However, IQ testing is not the only reason for this discriminatory practice. Although 50% of students in the United States are BIPOC, most teachers are White. White teachers disproportionately classify Black children (especially boys) as disruptive and aggressive, even when engaging in the same behaviors as their White peers (Association of Psychological Science, 2014).

In response to this problem, there are increasing numbers of initiatives designed to improve teacher education and the outcomes of their BIPOC students. For example, in 2012, New York City launched a program called the Expanded Success Initiative in 40 schools, which impacted 20,000 students. Teachers were trained to provide culturally relevant instruction that was more inclusive of the experiences of BIPOC students, especially males, and which encouraged social activism. Relationships between teachers and students were improved through extra-curricular experiences, and a sense of belonging to the school was also fostered through peer-tutoring. Students were given more academically rigorous instruction, and were helped with college preparation, including visits to colleges and help with applications. Students who participated in the programs felt that they were treated more fairly and felt more connected to their schools than students in schools who did not participate in the initiative (Villavicencio, 2023).

Modern-Day Intelligence Tests

Modern-day IQ tests are heavily influenced by the work of David Wechsler. In 1939, Wechsler created a new kind of intelligence test designed to tap a wider range of abilities than the original Stanford-Binet scale. After he graduated with a Bachelor’s degree from City College, CUNY, Wechsler became a private in the army where he administered some of the intelligence tests developed by Terman and his team (Boake, 2002; Saxon, 1981). Wechsler was struck by the fact that many army recruits, who functioned perfectly well in their skilled civilian jobs, scored way below average on the army intelligence tests (Boake, 2002). After the army, Wechsler earned a doctoral degree from Columbia University and became the chief psychologist at Bellevue Hospital in New York City. He became increasingly frustrated with the limitations of the Stanford-Binet scale and so decided to create a new measure of intelligence (Boake, 2002). Wechsler was particularly critical of the Stanford-Binet scale’s heavy reliance on verbal ability and the use of a single IQ score to measure general intelligence (Biswas-Diener, 2018). To try and address these issues, Wechsler created the Wechsler-Bellevue test, which was designed to test a wider range of cognitive abilities (Saxon, 1981). In 1955, Wechsler’s initial test was revised and renamed as the Wechsler Adult Intelligence Scale (WAIS; Saxon, 1981). The WAIS assessed people’s ability to remember, compute, understand language, reason well, and process information quickly (Biswas-Diener, 2018). Wechsler developed similar tests for children: The Wechsler Intelligence Scale for Children (WISC) in 1949, and the Wechsler Pre-School and Primary Scale of Intelligence (WPPSI) in 1967 (Saxon, 1981). Wechsler scales became more popular measures of intelligence than the Stanford Binet scale, in part, because they provided separate assessments of verbal and non-verbal skills. These scores were then summed together to provide a measure of IQ. However, just like Terman, Wechsler standardized all of these tests, using only White participants, which was a major shortcoming (Boake, 2002).

Since the 1930s, the various Wechsler and Stanford-Binet scales have been revised multiple times and newer versions are widely used today (Gibbons & Warne, 2019). The Stanford-Binet and Wechsler scales have also now been standardized using more diverse samples (Boake, 2002). The current versions of the Wechsler and Stanford-Binet scales (and serval other modern cognitive aptitude tests) have been greatly influenced by the Cattell-Horn-Carroll (CHC) theory of cognitive abilities (Schneider & McGrew, 2018). This comprehensive theory rests on the idea that general intelligence can be subdivided into at least 9-10 broad categories of cognitive abilities, some of which come under the general heading of fluid intelligence while others rely on crystallized intelligence (Cattell, 1963). These domains include quantitative knowledge; reading and writing; comprehension and general knowledge; fluid reasoning – the ability to solve novel problems; short-term memory, long-term memory, visual processing, auditory processing and processing speed. Each of these domains can be further subdivided into other abilities. Both the current version of the WAIS (WAIS IV) and the Stanford Binet (Stanford-Binet 5) aim to tap many of these abilities. The WAIS IV consists of 10 subtests, which yields four separate factor scores: perceptual reasoning, verbal comprehension, working memory and processing speed. The Stanford-Binet 5 yields five different factor measures: fluid reasoning, general knowledge, quantitative reasoning, visual-spatial reasoning, and working memory. However, despite these refinements, all of these tests were developed by White psychologists and reflect their cultural values (Washington et al., 2016). To underscore this point, in 1972, Black psychologist and professor, Dr. Robert Williams, designed the Black Intelligence Test of Cultural Homogeneity (B.I.T.C.H.), which focused on testing knowledge about the lives and culture of Black people in the US. Williams coined the term “ebonics” to describe the use of African American Vernacular English (AAVE) that he used in his test questions. As predicted, Black children and college students did much better on this test than their White counterparts (Williams, 1975).

Links to Learning

Learn more about the different subtests of the WAIS IV here

Watch this interview of Dr. Williams explaining why he developed the B.I.T.C.H. to show that culturally-specific language affects performance on tests designed to measure intelligence.

Researchers have underscored that many people misunderstand AAVE to be a form of broken English and a sign of low intelligence (Edwards, 2008). However, AAVE is a dialect of English, with roots in Africa. Just like any other language, it has a lexicon and a grammar, but these are different to those in standard English. Using AAVE does not indicate a lack of intelligence. Indeed, some researchers have argued that AAVE speakers who are also fluent in standard English are likely to have the same cognitive advantages as other bilinguals who switch between two languages (Edwards, 2008; Washington et al., 2023). However, most AAVE-speaking children, particularly those from working-class backgrounds, are not given the same educational support as other bilinguals when learning standard American English. This has been shown to impact reading and writing development (Washington et al., 2023). Julie Washington argues that many AAVE-speaking children are discouraged in school settings by teachers who lack cultural sensitivity and knowledge of AAVE. She has shown that culturally appropriate reading instruction improves the abilities of working class African American children who use AAVE (Washington et al., 2023).

Stereotype threat

We have already discussed some of the reasons why people from marginalized backgrounds may do poorly on IQ tests or other tests of cognitive aptitudes. In addition, people are vulnerable to a phenomenon known as stereotype threat. This is when people internalize negative stereotypes about themselves, which then negatively affects their performance (Stangor & Walinga, 2014). In 1995, two psychologists, Claude Steele and Joshua Aronson tested the hypothesis that the differences in performance on IQ tests between Blacks and Whites might be due to the activation of negative stereotypes about intelligence in Blacks (Steele & Aronson, 1995). They found that Black university students performed worse on standardized test questions when they were told that their verbal ability was being tested (thus the stereotype was activated). In contrast, their performance was not affected when the test was described simply as problem solving. They also found that when students were asked to write down their race before they took a math test, Black students performed more poorly than they had on prior exams, whereas White students were unaffected (Stangor & Walinga, 2014). Stereotype threat can also negatively impact women’s performance on math tests and exams (Marx & Roman, 2002; McIntyre et al., 2003). Importantly, stereotype threat is not absolute; we can reduce the feelings of self-doubt, by thinking about the positive characteristics that we (or a group with which we identify) possess (Johns et al., 2005; Marx & Roman, 2002; McIntyre et al., 2003). Just knowing that stereotype threat exists can help to alleviate its negative impact (Johns et al., 2005).

Measuring Intelligence Beyond IQ Tests

Diagram of theory. Central box says multiple intelligences - lines connect to 8 different circles, each representing a different type of intelligence. The circles contain the following text: LINGUISTIC - Good with language. LOGICAL-MATHEMATICAL - Good with numbers and solving problems. MUSICAL - Appreciates differences in pitch and rhythm. BODILY-KINESTHETIC - Understands bodily movement: dance/athletics. SPATIAL- can imagine how objects look in different positions; good at directions. INTERPERSONAL - understands and good with other people. INTRAPERSONAL - self-aware, understands own emotions. NATURALIST - understands nature
Figure 8.7. Gardner’s Theory of Multiple Intelligences

Many psychologists have argued that intelligence is not adequately measured by IQ tests. For example, Howard Gardner, a Harvard psychologist, believes that intelligence is extremely multi-faceted and should be broadly defined across multiple domains. In 1983, Gardner published a book explaining his Multiple Intelligences Theory (see Figure 8.7). In Gardner’s theory, each person possesses at least eight different kinds of intelligence. These include linguistic, logical-mathematical, musical, bodily kinesthetic, spatial, interpersonal, intrapersonal intelligence, and naturalistic intelligences (Gardner, 1983). Among cognitive psychologists, Gardner’s theory has been criticized for lacking empirical evidence. However, educators continue to study and use Gardner’s theory to improve learning experiences for students.

Robert Sternberg agreed with Gardener that there are multiple different types of intelligence. Sternberg developed a theory of intelligence, which he called the Triarchic theory of Intelligence because it conceives of intelligence as being comprised of three kinds (Sternberg, 1988): practical, creative, and analytical intelligence (Figure 8.8).

Figure 8.8. Sternberg’s theory identifies three types of intelligence: practical, creative, and analytical.

Practical intelligence is sometimes compared to “street smarts.” Being practical means you find solutions that work in your everyday life by applying knowledge based on your experiences. Analytical intelligence is closely aligned with academic problem solving and computational abilities. Creative intelligence is marked by inventing or imagining a solution to a problem or situation. Sternberg expected that someone’s background would have different effects on the three types of intelligence. Sternberg grouped student applicants to a summer program at Yale University according to their scores on the Triarchic Intelligence test. He found that more White middle-class students from well-resourced schools scored high on analytical intelligence, but there was much more diversity among people with high scores on practical intelligence or creative intelligence, in terms of their race/ethnicity and SES (Sternberg, 1999). Sternberg has worked with colleges to make admissions criteria more fair and found that creative intelligence was a much better predictor of first-year grade-point average than SAT scores (Sternberg & The Rainbow Project Collaborators, 2006). Importantly, Sternberg (1995) has also shown that practical intelligence may be a better predictor of career success than analytical intelligence. Sternberg has also pointed out that intelligence is subjective and culturally specific (Sternberg, 1999). Some cultures value cognitive intelligence over social intelligence, but the opposite is true in other cultures.

Gardner’s inter- and intrapersonal intelligences have often been combined by other psychologists into a single type: emotional intelligence. Emotional intelligence encompasses the ability to identify and understand the emotions of yourself and others, show empathy, understand social relationships and cues, and regulate your own emotions and respond in culturally appropriate ways (Mayer & Salovey, 1997; Parker et al., 2009). People with high emotional intelligence typically have well-developed social skills. Studies have shown a link between emotional intelligence and success, including job performance (Goleman, 1995; Lopes et al., 2006). However, emotional intelligence has been widely debated, with researchers pointing out that it is a concept that is difficult to measure and study empirically (Locke, 2005; Mayer et al., 2004).

Why are IQ tests still used?

As discussed in this chapter, there are many reasons as to why, on average, BIPOC people, especially African Americans and Latinx people, do less well than Whites on IQ tests and other standardized tests of cognitive ability, such as the SAT. In particular, IQ and SAT tests continue to use content that predominantly reflects White middle class values, not surprisingly, these tests lack predictive power about job and academic success for people of color (Berry et al., 2014; Helms et al., 2014). In particular, Au (2020) has argued that high-stakes standardized tests promote whiteness and undermine multicultural education. So, why and how are IQ and other cognitive skills test still used? One reason for a lack of change is that alternative conceptualizations of intelligence (other than IQ) are relatively hard to measure. Robert Sternberg has worked with various colleges and Universities to try and improve admissions criteria, but the research program is small and tests are time consuming to score (Sternberg et al., 2020; Sternberg and the Rainbow Project Collaborators, 2006). However, one of the very few benefits of the recent Covid-19 pandemic was that SAT testing was suspended and colleges and universities were unable to use the scores in their admissions decisions. SAT testing has now resumed, but a large number of institutions, including many Ivy leagues, are now questioning its value. Many colleges either no longer require SAT/ACT test results, or have decided to make testing optional. This change increased the diversity of admitted students at both Cornell and the University of Chicago (Einhorn, 2022). What do you think about this decision? What metrics do you think that colleges should use for admissions decisions?

The most common use of IQ tests is in educational settings to identify children who may need extra assistance in schools because of a learning disability. IQ tests, like the Stanford-Binet scale, are also used to identify gifted children for selective academic programs. Neuropsychologists also use IQ tests to identify cognitive issues following a head injury, stroke, or the onset of illnesses, such as dementia. In recognition of racial and socioeconomic differences in scores, many IQ tests now have different norms for different groups of people. However, some neuropsychologists have acknowledged that making adjustments to scores is a poor substitute for culture-fair testing (Byrd & Rivera-Mindt, 2022). Given the long entrenched history of many of these tests it is unlikely that change will occur rapidly, especially given that the majority of psychologists are White, and may lack the cultural awareness needed to spur transformative change (Hiermeier & Verity, 2022). However, psychologists of color like Dr. Desiree Byrd of Queens College, CUNY, are leading the way to make change.

Practice can increase intelligence (and IQ scores)

Given that IQ and other cognitive tests are likely to be around for a long time, it is helpful to know that cognitive abilities, just like other abilities, can improve with practice. When we learn and practice skills that help us to do better in school – we also do better on IQ tests (Nisbett et al., 2012). Performing any task (physical or mental) causes new connections between neurons to grow in the brain, these connections grow stronger with subsequent practice, making it easier and easier each time we repeat a task.

Link to Learning

Check out this video to remind yourself about what is happening in your brain when you learn something new.


Making mistakes and figuring out what to do differently next time is an important part of learning, though admittedly, sometimes it can be frustrating. The way a person thinks about making mistakes and their own intelligence is very important because it predicts how they perform in school and on IQ tests (Biswas-Diener, 2018; Dweck, 1986). Dr. Carol Dweck has focused her life’s work on looking at the differences between children who perform well in school and those who do not. Dweck found that children who believe that their abilities (including intelligence) are fixed and cannot change, tend to underperform. In contrast, kids who have a “growth mindset” and believe that intelligence is changeable and evolving, are able to handle failure and perform better in school (Dwek, 1986; Biswas-Diener, 2018).

Dig Deeper

Assess your mindset by taking this assessment based on Dweck’s work. What did you learn about yourself? Can you use the information in this book about neuroplasticity to shift toward a stronger growth mindset?

Link to Learning

Watch this video that compares different theories of intelligence to learn more.


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Introduction to Psychology (A critical approach) Copyright © 2021 by Jill Grose-Fifer; Rose M. Spielman; Kathryn Dumper; William Jenkins; Arlene Lacombe; Marilyn Lovett; and Marion Perlmutter is licensed under a Creative Commons Attribution 4.0 International License, except where otherwise noted.

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