Other researchers have proposed even more types of intelligences. Louis Thurstone (1938) proposed that there were seven clusters of primary mental abilities, made up of word fluency, verbal comprehension, spatial ability, perceptual speed, numerical ability, inductive reasoning, and memory. However, even these dimensions tend to be at least somewhat correlated, showing again the importance of g.

One advocate of the idea of multiple intelligences is the psychologist Robert Sternberg, who  proposed a triarchic theory of intelligence, focusing on three types of intelligence, and that people may display analytical intelligence, creative intelligence, and practical intelligence. Sternberg (1985, 2003b) argued that traditional intelligence tests assess analytical intelligence, the ability to answer problems with a single right answer, but that they do not assess creativity well, like the ability to adapt to new situations and create new ideas, or practicality, like the ability to write good memos or to effectively delegate responsibility.

As Sternberg proposed, research has found that creativity is not highly correlated with analytical intelligence (Furnham & Bachtiar, 2008), and exceptionally creative scientists, artists, mathematicians, and engineers do not score higher on intelligence than do their less creative peers (Simonton, 2000). Furthermore, the brain areas that are associated with convergent thinking, which is thinking that is directed toward finding the correct answer to a given problem, are different from those associated with divergent thinking (Tarasova, Volf, & Razoumnikova, 2010), which is the ability to generate many different ideas for or solutions to a single problem (Figure IL.3). On the other hand, being creative often takes some of the basic abilities measured by g, including the abilities to learn from experience, to remember information, and to think abstractly (Bink & Marsh, 2000).

The triarchic theory of intelligence has been criticized for lacking empirical support (Gottfredson, 2003). Sternberg’s assertion that existing intelligence tests fail to measure practical intelligence has also been questioned. Given that high IQ predicts higher income and career potential, it may be argued that it includes what is called “street smarts” or practical intelligence. Executive functioning may better account for some kinds of creative intelligence such as divergent thinking and that this may be separate from analytical thinking (Nusbaum, 2011).

Studies of creative people suggest at least five components that are likely to be important for creativity:

1. Expertise — Creative people have carefully studied and know a lot about the topic that they are working in. Creativity comes with a lot of hard work (Ericsson, 1998; Weisberg, 2006).
2. Imaginative thinking — Creative people often view a problem in a visual way, allowing them to see it from a new and different point of view.
3. Risk taking — Creative people are willing to take on new but potentially risky approaches.
4. Intrinsic interest — Creative people tend to work on projects because they love doing them, not because they are paid for them. In fact, research has found that people who are paid to be creative are often less creative than those who are not (Hennessey & Amabile, 2010).
5. Working in a creative environment — Creativity is in part a social phenomenon. Dean Simonton (1992) found that the most creative people were supported, aided, and challenged by other people working on similar projects.

The last aspect of the triarchic model, practical intelligence, refers primarily to intelligence that cannot be gained from books or formal learning. Practical intelligence represents a type of common sense that is learned from life experiences. Although a number of tests have been devised to measure practical intelligence (Sternberg, Wagner, & Okagaki, 1993; Wagner & Sternberg, 1985), research has not found much evidence that practical intelligence is distinct from g or that it is predictive of success at any particular tasks (Gottfredson, 2003). Practical intelligence may include, at least in part, certain abilities that help people perform well at specific jobs, and these abilities may not always be highly correlated with general intelligence (Sternberg, Wagner, & Okagaki, 1993). On the other hand, these abilities or skills are very specific to particular occupations and thus do not seem to represent the broader idea of intelligence.

Another supporter of the idea of multiple intelligences is the psychologist Howard Gardner. Gardner (1983, 1999) argued that it would be evolutionarily functional for different people to have different talents and skills. Additionally, Gardner proposed that there are eight intelligences that can be differentiated from each other, as seen in the table below. Gardner noted that some evidence for multiple intelligences comes from the abilities of “autistic savants,” people who may score low on intelligence tests overall but who nevertheless may have exceptional skills in a given domain, such as math, music, art, or in being able to recite statistics in a given sport (Treffert & Wallace, 2004). Zohar (1997) suggested that there may be a 9th intelligence called “spiritual intelligence”. Gardener (2000) did not include this in his list of multiple intelligences due to a lack of quantifiable data while acknowledging that “existential intelligence” might be an option (Allen & Shearer, 2013). This intelligence has been hypothesized to include self-awareness, being a visionary, showing compassion, and sense of purpose (Zohar, 2000).

Table adapted from Gardner (1999).

The idea of multiple intelligences has been influential in the field of education, and teachers have used these ideas to try to teach differently to different students (Figure IL.4). For instance, to teach math problems to students who have particularly good kinesthetic intelligence, a teacher might encourage the students to move their bodies or hands according to the numbers. On the other hand, some have argued that these intelligences sometimes seem more like abilities or talents rather than real intelligence, and there is no clear conclusion about how many intelligences there are. Are sense of humour, artistic skills, dramatic skills, and so forth also separate intelligences? Furthermore, and again demonstrating the underlying power of a single intelligence, the many different intelligences are in fact correlated and thus represent, in part, the general intelligence factor (Brody, 2003).

In addition, there is limited  empirical evidence for  multiple intelligences. (Visser et al., 2006). Gottfredson (2006) shows that  the empirical support  for multiple intelligences is weak while IQ appears to predict numerous life outcomes.

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 construct 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 some of 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 life. Numerous statistical procedures that are used today come from the early attempts to study intelligence and measure it accurately. While these early intelligence tests may not have been accurate and have often contributed to negative group stereotypes, the statistical and experimental procedures that they helped to establish are of use today.

Intelligence changes with age. A three-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. Once a large enough representative sample of people have been tested, any individual’s score can be compared to norms that are based on the population.

The intelligence tests that you may be most familiar with are aptitude tests, which are designed to measure one’s ability to perform a given task, such as doing well in undergraduate, graduate, or post-graduate training. Canadian post-secondary institutions request official high school transcripts demonstrating minimum grade admission requirements, while most American colleges and universities require students to take the Scholastic Assessment Test (SAT) or the American College Test (ACT). Post-graduate schools in both countries sometimes require the Graduate Record Examination (GRE), Graduate Management Admission Test (GMAT), Medical College Admissions Test (MCAT), or the Law School Admission Test (LSAT). These tests are useful for selecting students because they predict success in the programs that they are designed for, particularly in the first year of the program (Kuncel, Hezlett, & Ones, 2010). These aptitude tests also measure, in part, intelligence. Meredith Frey and Douglas Detterman (2004) found that the SAT correlated highly (i.e., between about r = .7 and r = .8) with standard measures of intelligence.Intelligence tests are also used by industrial and organisational psychologists in the process of personnel selection. Personnel selection is the use of structured tests to select people who are likely to perform well at given jobs (Schmidt & Hunter, 1998). The psychologists begin by conducting a job analysis in which they determine what knowledge, skills, abilities, and personal characteristics (KSAPs) are required for a given job. This is normally accomplished by surveying or interviewing current workers and their supervisors. Based on the results of the job analysis, the psychologists choose selection methods that are most likely to be predictive of job performance. Measures include tests of cognitive and physical ability and job knowledge tests, as well as measures of IQ and personality.

The biology of intelligence

Is intelligence nature or nurture?

Intelligence has both genetic and environmental causes, and these have been systematically studied through a large number of twin and adoption studies (Neisser et al., 1996; Plomin, 2003). These studies have found that between 40% and 80% of the variability in IQ is due to differences in genes, meaning that overall, genetics plays a bigger role than environment does in creating IQ differences among individuals (Plomin & Spinath, 2004). The IQs of identical twins correlate very highly, where r = .86, which is much higher than do the scores of fraternal twins who are less genetically similar, where r = .60, and the correlations between the IQs of parents and their biological children, where r = .42, is significantly greater than the correlation between parents and adopted children, where r = .19. The role of genetics gets stronger as children get older. The intelligence of very young children that are less than 3 years old does not predict adult intelligence, but by age 7 it does, and IQ scores remain very stable in adulthood (Deary, Whiteman, Starr, Whalley, & Fox, 2004).

There is also evidence for the role of nurture, indicating that individuals are not born with fixed, unchangeable levels of intelligence. Twins raised together in the same home have more similar IQs than do twins who are raised in different homes, and fraternal twins have more similar IQs than do non-twin siblings, which is likely due to the fact that they are treated more similarly than non-twin siblings are.

The fact that intelligence becomes more stable as we get older provides evidence that early environmental experiences matter more than later ones. Environmental factors also explain a greater proportion of the variance in intelligence for children from lower-class households than they do for children from upper-class households (Turkheimer, Haley, Waldron, D’Onofrio, & Gottesman, 2003). This is because most upper-class households tend to provide a safe, nutritious, and supporting environment for children, whereas these factors are more variable in lower-class households. For example, upper-class households tend to be in areas with more security and police protection. They are also less likely to be in food deserts. Lower income neighbourhoods are more likely to have fewer options for buying food or may be in food deserts where there are no convenient places to buy food within walking distance.

Social and economic deprivation can adversely affect IQ. Children from households in poverty have lower IQs than do children from households with more resources even when other factors such as education, race, and parenting are controlled (Brooks-Gunn & Duncan, 1997). Poverty may lead to diets that are less nourishing or lacking in appropriate vitamins, and poor children may also be more likely to be exposed to toxins such as lead in drinking water, dust, or paint chips (Bellinger & Needleman, 2003). These factors can slow brain development and reduce intelligence.

If impoverished environments can impact intelligence, we might wonder whether enriched environments can improve it. Government-funded after-school programs such as Head Start are designed to help children learn. Head Start is a government initiative in the United States which is aimed at providing early childhood education, nutrition, and other services to low-income families. Research has found that attending such programs may increase intelligence for a short time, but these increases rarely last after the programs end (McLoyd, 1998; Perkins & Grotzer, 1997). Other studies suggest that Head Start and similar programs may improve emotional intelligence and reduce the likelihood that children will drop out of school or be held back a grade (Reynolds, Temple, Robertson, & Mann 2001).

Intelligence is improved by education; the number of years a person has spent in school correlates at about r = .6 with IQ (Ceci, 1991). In part, this correlation may be due to the fact that people with higher IQ scores enjoy taking classes more than people with low IQ scores, and thus they are more likely to stay in school. In large classes, teachers are not able to give enough of their time to students who do not perform well in academic subjects. This in turn leads to the students getting discouraged with school and academia in general. However, education also has a correlational effect on IQ. Comparisons between children who are almost exactly the same age but who just do or just do not make a deadline for entering school in a given school year show that those who enter school a year earlier have higher IQ than those who have to wait until the next year to begin school (Baltes & Reinert, 1969; Ceci & Williams, 1997). Children’s IQs tend to drop significantly during summer vacations (Huttenlocher, Levine, & Vevea, 1998), a finding that suggests that a longer school year, as is used in Europe and East Asia, is beneficial.

It is important to remember that the relative roles of nature and nurture can never be completely separated. A child who has higher than average intelligence will be treated differently than a child who has lower than average intelligence, and these differences in behaviours will likely amplify initial differences. This means that modest genetic differences can be multiplied into big differences over time.

Psychology in Everyday Life

Emotional intelligence

Although most psychologists have considered intelligence a cognitive ability, people also use their emotions to help them solve problems and relate effectively to others. While there are different models of emotional intelligence, the term encompasses the ability to accurately identify, assess, and understand emotions, both of oneself and others, and to effectively regulate one’s own emotions (Ackley, 2016).

The idea of emotional intelligence is seen in Howard Gardner’s interpersonal intelligence (the capacity to understand the emotions, intentions, motivations, and desires of other people) and intrapersonal intelligence (the capacity to understand oneself, including one’s emotions). Public interest in, and research on, emotional intelligence became widely prevalent following the publication of Daniel Goleman’s best-selling book, Working With Emotional Intelligence (1998).

One problem with emotional intelligence tests is that they often do not show a great deal of reliability or construct validity (Føllesdal & Hagtvet, 2009). Although it has been found that people with higher emotional intelligence are also healthier (Martins, Ramalho, & Morin, 2010), findings are mixed about whether emotional intelligence predicts life success, for instance, in job performance (Harms & Credé, 2010). Other researchers have questioned the construct validity of the measures, arguing that emotional intelligence really measures knowledge about what emotions are, but not necessarily how to use those emotions (Brody, 2004). These same researchers claim that emotional intelligence is actually a personality trait, a part of the general intelligence factor, or a skill that can be applied in some specific situations, for instance, academic and work situations (Landy, 2005).

Although measures of the ability to understand, experience, and manage emotions may not predict effective behaviours, another important aspect of emotional intelligence —emotion regulation — does. Emotion regulation refers to the ability to control and productively use one’s emotions. Research has found that people who are less impulsive and better able to override their impulses to seek immediate gratification also have higher cognitive and social intelligence. They have better test scores, are rated by their friends as more socially adept, and cope with frustration and stress better than those with less skill at emotion regulation (Ayduk et al., 2000; Eigsti et al., 2006; Mischel & Ayduk, 2004).

Because emotional intelligence seems so important, many school systems have designed programs to teach it to their students. However, the effectiveness of these programs has not been rigorously tested, and we do not yet know whether emotional intelligence can be taught or if learning it would improve the quality of people’s lives (Mayer & Cobb, 2000). Many businesses and corporations have an interest in emotional intelligence in relation to job performance, leadership, and flexibility (Ackley, 2016).

Image Descriptions

Figure IL.2 Carroll’s Three Stratum Model of Human Intelligence image description: It is organised into three categories: General (Stratum III), Broad (Stratum II), and Narrow (Stratum I).

• g –  General (Stratum III)
  • Gf – Broad (Stratum II)
    • f1 – Narrow (Stratum I)
    • f2
    • f…
  • Gc – Broad (Stratum II)
    • c1 – Narrow (Stratum I)
    • c2
    • c…
  • Gy – Broad (Stratum II)
    • y1 – Narrow (Stratum I)
    • y2
    • y…
  • Gv – Broad (Stratum II)
    • v1 – Narrow (Stratum I)
    • v2
    • v…
  • Gu – Broad (Stratum II)
    • u1 – Narrow (Stratum I)
    • u2
    • u…
  • Gr – Broad (Stratum II)
    • r1 – Narrow (Stratum I)
    • r2
    • r…
  • Gs – Broad (Stratum II)
    • s1 – Narrow (Stratum I)
    • s2
    • s…
  • Gt – Broad (Stratum II)
    • t1 – Narrow (Stratum I)
    • t2
    • t… [Return to Figure IL.2]

Image Attributions

Figure IL.1. Az-Writing Boy E-Citizen by Moonsun1981 is used under a CC BY-SA 3.0 license.

Figure IL.2. From Three-Stratum Theory, by T. Bates, 2013. Carroll’s Three Stratum Model of Human Intelligence by Tim bates is licensed under a CC BY-SA 3.0 license.

Figure IL.3. Wanzikia by Hawyih is in the public domain.

Figure IL.4. Klutz the Clown by Herald Post is used under a CC BY-NC 2.0 license; Women Heptathlon LJ French Athletics Championships 2013 t144221 by Marie-Lan Nguyen is used under a CC BY 3.0 license; Street Painter by Pedro Ribeiro Simões is used under a CC BY 2.0 license; Vardan Mamikonyan Armenian Pianist by Chaojoker is used under a CC BY-SA 3.0 license; Teacher at Chalkboard by cybrarian77 is used under a CC BY-NC 2.0 license.\

Figure IL.5. Figure 5.13 as found in Lifespan Development chapter: Extremes of Intelligence: Intellectual Disability and Giftedness is licensed under a CC BY-NC-SA 4.0 license.

Figure IL.6. Figure 9.1.4 as found in Introduction to Psychology (Libretexts) is shared under a CC BY-NC-SA 3.0 license and was authored, remixed, and/or curated by Anonymous via source content that was edited to the style and standards of the LibreTexts platform.

Figure IL.7. Figure 9.1.5 as found in Introduction to Psychology (Libretexts) is shared under a CC BY-NC-SA 3.0 license and was authored, remixed, and/or curated by Anonymous via source content that was edited to the style and standards of the LibreTexts platform.