In the United States, intelligence is often associated with “book smarts.” We think of “intelligent” people as those who score high on tests measuring academic abilities. But intelligence is more complicated than that—so complicated, in fact, that psychologists have yet to agree on its precise definition. It is not even clear whether intelligence is a single unified entity, or a collection of capabilities.
We do know that intelligence is, to a certain degree, a cultural construct. We have already noted that people in America tend to equate intelligence with school smarts, but this is not the case everywhere in the world. Children living in a village in Kenya, for example, grow up using herbal medicine to treat parasitic diseases in themselves and others. Identifying illness and developing treatment strategies is a regular part of life. These children would score much higher on tests of intelligence relating to practical knowledge than on tests assessing vocabulary (Sternberg, 2004).
Even within a single culture, the meaning of intelligence changes across time. “Intelligence” for modern Kenyans may differ from that of their 14th-century ancestors.
As we explore this topic further, please keep in mind that intelligence does not always go hand in hand with intelligent behavior. People can score high on intelligence measures but exhibit a low level of judgment. Psychologists and educators must be careful to distinguish between test scores and everyday smarts.
Survival Smarts Maasai children in Kenya go through the motions of starting a fire. Definitions of intelligence vary according to culture. In the United States, intelligence is typically associated with high grades and test scores. Elsewhere in the world, being “smart” may have more to do with knowing how to survive and stay healthy.
Logical-mathematical Scientist Mathematician Sensitivity to, and capacity to discern, logical or numerical patterns; ability to handle long chains of reasoning.
Linguistic Poet Journalist Sensitivity to the sounds, rhythms, and meanings of words; sensitivity to the different functions of language.
Musical Composer Violinist Abilities to produce and appreciate rhythm, pitch, and timbre; appreciation of the forms of musical expressiveness.
Spatial Navigator Sculptor Capacities to perceive the visual-spatial world accurately and to perform transformations on one’s initial perceptions.
Bodily-kinesthetic Dancer Athlete Abilities to control one’s body movements and to handle objects skillfully.
Interpersonal Therapist Salesman Capacities to discern and respond appropriately to the moods, temperaments, motivations, and desires of other people.
Intrapersonal Person with detailed, accurate self-knowledge Access to one’s own feelings and the ability to discriminate among them and draw upon them to guide behavior; knowledge of one’s own strengths, weaknesses, desires, and intelligences.
This table reprinted with permission from Gardner and Hatch (1989) presents Gardner’s original 7 intelligences. Each intelligence has associated strengths and capabilities.
SOURCE: GARDNER AND HATCH (1989).
Robert Sternberg (1988) proposed three kinds of intelligence. Sternberg’s triarchic theory of intelligence(trī-är-kik) suggests that humans have varying degrees of analytical, creative, and practical competencies (Figure 7.6). Analytic intelligence refers to our capacity to solve problems. Creative intelligence represents the knowledge and skills we use to handle new situations. Practical intelligence includes our ability to adjust to different environments.
There is a general intelligence driving abilities in many areas.
There are eight types of intelligences, which go beyond academic smarts and scholarship
There are eight types of intelligences, which go beyond academic smarts and scholarship.
Humans have varying degrees of analytical, creative, and practical competencies.
Intelligence testing has an extensive history. In 1904 psychologist Alfred Binet (1857-1911) joined a commission of the French government that sought to create a way to identify students who might have trouble learning in regular classroom settings. A new French law had recently required school attendance by all children. The Minister of Public Instruction recognized that this transition would be difficult because some French children had never attended school. For the law to be implemented successfully, it was necessary to identify who had potential to succeed. A measure was needed to predict the performance of these schoolchildren (Fancher & Rutherford, 2012; Watson, 1968).
Binet worked with one of his students, Théodore Simon, to construct an assessment of intelligence. They studied Binet’s daughters and Parisian schoolchildren, coming up with the 30 items in the original assessment. These items were designed to be of increasing difficulty, starting with a simple test to see if a child could follow a lit match that the tester moved in front of her. The items became more difficult as testing progressed (explaining how paper and cardboard are different, making rhymes with words; Fancher & Rutherford, 2012).
Binet and Simon assumed that children generally follow the same path of intellectual development. Their primary goal in creating their assessment was to compare the mental ability of an individual child with the mental abilities of other children of the same age. They would determine the
This method does not apply to adults, however. It wouldn’t make sense to give a 60-year-old man who scores the same as a 30-year-old man an IQ score of 50 (that is, 30 ÷ 60 × 100 = 50). Modern intelligence tests still assign a numerical score (which we continue to refer to as “IQ”), although they no longer use the actual quotient score.
American psychologist Lewis Terman (1916) revised Stern’s work so that Binet’s test could be used in the United States, where it came to be known as the Stanford-Binet. Terman changed some items, added items, developed standards based on American children, and extended the test to include teens and adults. The Stanford-Binet Intelligence Scales, as it is now known in its fifth edition (Roid, 2003), includes the assessment of verbal and nonverbal abilities (for instance, defining words, tracing paths in a maze). The Stanford-Binet yields an overall score for general intelligence, as well as scores relating to more specific abilities, such as knowledge, reasoning, visual processing, and working memory (Becker, 2003).
In the late 1930s, David Wechsler began creating intelligence tests for adults (Anastasi & Urbina, 1997). Wechsler noted that the Stanford-Binet was designed exclusively for children. And although many had been using the Stanford-Binet with adults, it was not an ideal measure, given that adults might not react positively to the questions geared to the daily experiences of school-age children. The Wechsler Adult Intelligence Scale (WAIS) was published in 1955 and has since been revised numerous times (1981, 1997), with the most recent revision in 2008 (WAIS-IV). In addition to creating assessments for adults, Wechsler also developed scales for older children (Wechsler Intelligence Scale for Children, WISC-IV) and younger children (Wechsler Preschool and Primary Scale of Intelligence, WPPSI-III).
The Wechsler assessments of intelligence consist of a variety of subtests designed to measure different aspects of intellectual ability. The 10 subtests on the WAIS-IV target four domains of intellectual performance: verbal abilities, perceptual reasoning, working memory, and processing speed. Results from the WAIS-IV include an overall IQ score, as well as scores on the four domains. Psychologists look for consistency among the domain scores and subtest scores. Substantial inconsistency may suggest an issue that should be further explored, such as a reading or language disability. In the United States, Wechsler tests are now used more frequently than the Stanford-Binet.
One primary characteristic of a measure of intelligence is validity. This is the degree to which the assessment measures what it intends to measure. We can assess the validity of a measure by comparing its results to those of other assessments that have been found to measure the factor of interest. In addition, we determine the validity of a measure by seeing if it can predict what it is designed to measure, or its predictive validity. Thus, to determine if an intelligence test is valid, we would check to see if the scores it produces are consistent with those of other intelligence tests. A valid intelligence test should also be able to predict future performance on tasks related to intellectual ability.
Another important characteristic of assessment is reliability, the ability of a test to provide consistent, reproducible results. If given repeatedly, a reliable test will continue producing the same types of scores. If we administer an intelligence test to an individual, we would expect (if it is reliable) that the person’s scores will remain consistent across time. We can also determine the reliability of an assessment by splitting the test in half and then determining whether the findings of the first and second halves of the test agree with each other. It is important to note that it is possible to have a reliable test that is not valid. For this reason, we always have to determine both reliability and validity.
In addition to being valid and reliable, a good intelligence test provides standardization. Perhaps you have taken a test that measured your achievement in a particular area (for example, an ACT or SAT), or an aptitude test to measure your innate abilities (for example, an IQ test). Upon receiving your scores, you may have wondered how you performed in comparison to other people in your class, your college, or your state. Most aptitude and achievement tests allow you to make these judgments through the use of standardization. Standardization occurs when test developers administer a test to a large sample of people and then publish the average scores, or norms, for specified groups. The test developers provide these norms using a sample that is representative of the population of interest. It is important that the sample include a variety of individuals who are similar to the population using the test. This allows you to compare your own score with people of the same age, gender, socioeconomic status, or region. With test norms, you are able to make judgments about the relative performance (often provided as percentiles) of an individual compared to others with similar characteristics.
It is also critical that assessments are given and scored using standard procedures. This ensures that no one is given an unfair advantage or disadvantage in terms of testing conditions. Intelligence tests are subject to tight control. The public does not have access to the questions or answers, and all testing must be administered by a professional. What about those IQ tests found on the Internet? They simply are not valid due to lack of standardization.
Have you ever wondered how many people in the population are really smart? Or perhaps how many people have average intelligence? With aptitude tests like the Wechsler assessments and the Stanford-Binet, we can predict what percentage of the population will have scores between two intervals by using a normal curve, which depicts the frequency of values along a continuum (Infographic 7.4). The normal curve is symmetrical and shaped like a bell. The highest point on the graph reflects the average score.
The normal curve shown in Infographic 7.4 portrays the distribution of scores for the Wechsler tests. As you can see, the mean or average score is 100. As you follow the horizontal axis, notice that the higher and lower scores occur less and less frequently in the population. A score of 145 or 70 is far less common than a score of 100, for example.
One final note about the normal curve is that it applies to a variety of characteristics, including IQ, height, weight, and personality characteristics), and that we use it to make predictions about these characteristics. Consult Appendix A for more information on the normal curve and a variety of other topics associated with statistics.
It has not yet been determined whether group differences on IQ scores also reflect biases of the tests themselves. Can an assessment be valid for some groups, but not others? For example, are these IQ tests solely aptitude tests, or do they incorporate some level of achievement (learned content)? If that is the case, then people with limited exposure to certain types of test content may be at a disadvantage. Early versions of the IQ tests exhibited some bias against individuals from rural areas, people of lower socioeconomic status, as well as African Americans. Bias may result from language, dialect, or the culture of those who have created the tests (Sattler, 1990; Sternberg, 2004).
How Smart Are Intelligence Tests?
Ultimately, IQ tests are good at predicting academic success. They are highly correlated with SATs, ACTs, and GREs, for example, and the correlations are stronger for the higher and lower ranges of IQ scores. Strong correlations help us make predictions about future behavior. Researchers have found, however, that self-discipline may be a better predictor of success than IQ tests (Duckworth & Seligman, 2005).
The study of intelligence is far from straightforward. Assessing a concept with no universally accepted definition is not an easy task, but these tests do serve useful purposes. The key is to be mindful of their limitations, while appreciating their ability to measure an array of cognitive abilities.
There are many causes of intellectual disability, but we cannot always pinpoint them. According to the American Association on Intellectual and Developmental Disabilities (AAIDD), nearly half of intellectual disability cases have unidentifiable causes (Schalock et al., 2010). We do know the causes for Down syndrome (an extra chromosome in what would normally be the 21st pair), fetal alcohol syndrome (exposure to alcohol while in utero), and fragile X syndrome (a defect in a gene on the X chromosome leading to reductions in protein needed for development of the brain). There are also known environmental factors, such as lead and mercury poisoning, lack of oxygen at birth, various diseases, and exposure to drugs during fetal development.
At the other end of the intelligence spectrum are the intellectually gifted, those who have IQ scores of 130 or above. Above 140, one is considered a “genius.” As you might imagine, very few people—about 2% of the population—are classified as gifted. An even smaller proportion falls in the genius range: only the top 1% of the population (Simonton, 2012). What roles do you think these gifted people take on in our society?
According to Goleman (1995), emotional intelligence has a major impact on everyday functioning. Someone with high emotional intelligence shows self-control; has the ability to manage anger, impulsiveness, and anxiety. She exhibits empathy, awareness of emotions, and persistent self-motivation. Research suggests that emotional intelligence is related to performance on the job and at school (MacCann, Fogarty, Zeidner, & Roberts, 2011). An example of someone with emotional intelligence is Dr. Jill Bolte Taylor.
While we are on the topic of nature and nurture, let’s examine how these two forces impact intelligence in general. Twin studies (research involving identical and fraternal twins) are an excellent way to examine the relative weights of nature and nurture for virtually any psychological trait. The Minnesota twin studies (Johnson & Bouchard, 2011; McGue, Bouchard, Iacono, & Lykken, 1993) indicate there are strong correlations between the IQ scores of identical twins—stronger than the correlations between the IQ scores of fraternal twins or other siblings. In other words, the closer the degree of the genetic relationship (identical twins have identical genes), the more similar their IQ scores are. This suggests that genes play a major role in determining intellectual abilities. According to the Minnesota twin studies, identical twins’ IQ scores have correlations as high as .86 (remembering that ±1.00 is a perfect correlation) (Figure 7.8).
FIGURE 7.8The Impact of Nature and Nurture on IntelligenceThe most genetically similar people, identical twins, have the strongest correlation between their scores on IQ tests. This suggests that genes play a major role in determining intelligence. But if identical twins are raised in different environments, the correlation is slightly lower, showing some environmental effect (McGue et al., 1993).
It is important to emphasize that heritability applies to groups of people, not individuals. We cannot say, for example, that an individual’s intelligence level is 40% due to genes and 60% the result of environment. We can only make general predictions about groups and how they are influenced by genetic factors (Dickens & Flynn, 2001).
We have now explored the various approaches to assessing intelligence. Let’s shift our focus to a quality that is associated with intelligence but far more difficult to measure.
Most psychologists agree that there are several basic characteristics associated with creativity (Baer, 1993; Sternberg, 2006a, 2006b):
Originality: the ability to come up with unique solutions when trying to solve a problem
Fluency: the ability to create many potential solutions
Flexibility: the ability to use a variety of problem-solving tactics to arrive at solutions
Knowledge: a sufficient base of ideas and information
Thinking: the ability to see things in new ways, make connections, see patterns
Personality: characteristics of a risk taker, who perseveres and tolerates ambiguity
Intrinsic motivation: influenced by internal rewards, motivated by the pleasure and challenge of work
Because it doesn’t present itself in a singular or uniform manner, creativity is difficult to measure. One way to assess creativity is to add up the number of times an individual exhibits the four characteristics of originality, fluency, flexibility, and elaboration in a problem-solving situation and then use these data to create a creativity score (Baer, 1993).
Creativity comes with many benefits. People with this ability tend to have a broader range of knowledge and interests. They are open to new experiences and tend to be uninhibited in thoughts and behaviors (Feist, 2004; Simonton, 2000). The good news is that we can become more creative by practicing divergent thinking, taking risks, and looking for unusual connections between ideas (Baer, 1993).
Sometimes finding those new connections takes a little relaxing on the part of the brain. Let’s see how this phenomenon might come into play by peering into the brain of a rapper.