Two Theories on The Nature of Intelligence

In the last decade of the nineteenth century, a French physician named Alfred Binet was commissioned by the school system to developa way to differentiate those students who were uneducable, or severely mentally handicapped, from the other students. He developedan intelligence test to do so. The very first intelligence tests, introduced a decade earlier, emphasized sensory tasks, physicalmeasures, and simple processes. Unlike these tests, Binet developed an intelligence test that consisted of items that required complexprocesses of the mind and examined the comprehensive individual. Consequently, the results from Binet’s scales were successful in discriminating between the two types of students.

The success of Binet’s test led to a much greater question to be asked: what exactlyare these tests measuring? What the tests claimed to measure was intelligence. But, if they measured intelligence, then the nextquestion that arose was this: what exactly is intelligence? It is at this point that the great debate on the definition of intelligence began there is a general consensus that there are different levels of intelligence, and that different individuals have different capacities of intelligence. In other words, “individuals differ from one Another in their ability to understand complex ideas, to adapt effectively to the environment, to learn from experience, to engage in various forms of reasoning, to overcome obstacles by taking thought” (Neisser et al., 1996, p. 77). But, how many and what kinds of different types of intelligences exist, and how to define intelligence, is still at debate.

Today, there are two major schools of thought on the nature of intelligence. The first, supported by such psychologists as Eysenck, Galton, Jensen, and Spearman, believe that all intelligence comes from one general factor, known as g. The proponents of the other school of thought include Gardner, Sternberg, and Thurstone. These psychologists think that there is more than one general type of intelligence, or in other words, that there are different types of intelligences. An interesting note about this school of thought is that there is disagreement, even within that camp, on exactly how many different types of intelligences there are.

One General Intelligence

There are strong arguments to support the theory of one general type of intelligence. The most convincing Evidence for a single general intelligence model is the fact that there is proof of a single general factor that governs the level of intelligence of an individual. This is also known as the positive manifold (Spearman, 1904). Furthermore, there is a very high correlation between IQ and very simple cognitive tasks, which supports the theory of one general intelligence (Eysenck, 1982).Positive manifold. The first argument in support of one general intelligence is the fact that there is a high positive correlation between different tests of cognitive ability. Spearman (1904), in doing His research, administered to many people different types of tests, covering several different areas of cognitive ability. When he examined the results of these different tests, he found that there was a positive correlation between the tests for a given individual. In other words, if a certain person performed well on a test of verbalabilities, then that same person also performed well on another test of another cognitive ability, for instance, a mathematics test. Spearman named this positive correlation among tests the positive manifold. This positive manifold was also called the general intelligence factor, or g. This is the single factor that determines the intelligence of the individual. Jensen (1997) supported the theory of one general intelligence by stating, “the positive correlation between all cognitive test items is a given, an inexorable fact of nature. The all-positive inter item correlation matrix is not an artifact of test construction or item selection, as Some test critics mistakenlybelieve” (p. 223). This positive manifold led Spearman (1904) to find a large first factor that was dubbed general intelligence, or g reaction time and g. Another strong argument in support of one general intelligence is the fact that there is a very high correlation between reaction time and IQ. According to Eysenck (1982), “IQ correlates very highly (.8 and above, without correction for attenuation) with tests which are essentially so simple, or even directly physiological that they can hardly be considered cognitive in the accepted sense” (p. 9). For instance, an example of the type of tests used to measure reaction time is a test in which a light is turned on. The participant is asked to press a button as soon as he or she sees the light go on. From tests such as these, the reaction time can be measured. Given that only very simple sensory and motor movements are necessary to respond, it is difficult to argue that cultural, environmental, gender, socio-economic, or educational discrepancies will affect the participants ability to respond to the testers” questions (Eysenck, 1982) common definitions of intelligence are “success in problem solving, ability to learn, capacity for producing noegenetic solutions, understanding of complex instructions or simply all-round cognitive ability” (Eysenck, 1982, p. 8).

A common thread in all of these definitions of intelligence is that they all require the nervous system, especially the brain, and sensory organs to be functioning properly. Furthermore, in order for these types of tasks to be completed, they require that the informationprocessing that goes on within the bodily systems is relatively without error.Jensen (1993), as well as others, synthesized these factsand conjectured that “the most obvious hypothesis is that speed of information processing is the essential basis if g, and one possibleneurological basis of speed of processing is the speed of transmission through nerve pathways” (p. 54). The speed of information transmission can be reasonably well measured or extrapolated from reaction time scores. Therefore, if an individual has faster neural processing speed, then he or she have a better reaction time. In turn, given that reaction time is highly correlated with IQ, then those individuals with faster neural processing speeds have higher IQ’s. Consequently, neural processing speed determines the level of intelligence of the individual; this intelligence is the one general intelligence, g.Summary. Sternberg and Gardner (1982) summarized the theory of one general intelligence by stating “general intelligence can be understood componentially as deriving in part from the execution of general components in information processing behavior” (p. 251). And Spearman (1973/1923) concluded that “cognitive events do, like those of physics, admit throughout of being reduced to a small number of definitely formulatable principles in the sense of ultimate laws” (p. 341). These psychologists, as well as many others, believe that intelligence can be defined by a single factor. Whether that single factor be termed positive manifold, neural processing speed, or g, the complexities of the human mind and its processes can be reduced to a single factor, defined as intelligence multiple Intelligences.

The different proponents of one general intelligence all agree that there is a single factor that determines intelligence, and the proponents of multiple intelligences agree that there is more than one single type of intelligence. However, the different proponents of multiple intelligences do not agree on how many different intelligences there are, or could be. I believe that the theories put forth by Gardner and Sternberg have the most merit. Both of them have their own theory on multiple intelligences; Gardner (1983) believes there are seven forms of intelligence; Sternberg (1985) believes there are three forms of intelligences.

Gardner’s Theory

Gardner’s theory of multiple intelligences suggests that there are seven different forms of intelligence. They are linguistic, musical, spatial, bodily, interpersonal, intrapersonal and logico mathematical. In developing his theory, Gardner (1983) attempted to rectify some of the errors of earlier psychologists who “all ignore[d] biology; all fail[ed] to come to grips with the higher levels of creativity; and all [were] insensitive to the range of roles highlighted in human society” (p. 24). So, Gardner based his own theory of intelligence on biological facts. Li (1996) summarizes Gardner’s theory as follows Premise 1: If it can be found that certain brain parts can distinctively map with certain cognitive functioning (A), then that cognitive functioning can be isolated as one candidate of multiple intelligences (B). (If A, then B). Premise 2: Now it has been found that certain brain parts do distinctively map with certain cognitive functioning, as evidenced by certain brain damageleading to loss of certain cognitive function. (Evidence of A).Conclusion: Therefore, multiple intelligences. (Therefore B.). (p. 34)

Gardner’s theory has a very solid biological basis. Premise two takes into account the brain as a major physical determinant of intelligence. By studying individuals who had speech impairment, paralysis, or other disabilities, Gardner could localize the parts of the brain that were needed to perform the physical function. He studied the brains of people with disabilities postmortem and found that there was damage in specific areas, in comparison to those who did not have a disability. Gardner found seven different areas of the brain, and so his theory consists of seven different intelligences, Each related to a specific portion of the human brain (Li, 1996).Gardner looked to develop a theory with multiple intelligences also because he felt that the current psychometric tests only examined the linguistic, logical, and some aspects of spatial intelligence, whereas the other facets of intelligent behavior such as athleticism, musical talent, and social awareness were not included (Neisser et al., 1996).Sternberg’s theory. The triarchic theory of intelligence developed by Sternberg is “a comprehensive theory, more encompassing. . . because it takes into account social and contextual factors apart from human abilities” (Li, 1996, p. 37). Sternberg (1985) felt that the theories that preceded him were not incorrect, but, rather, incomplete.

Consequently, his theory, like Gardner’s, takes into account creative or musical intelligence. But as for the other six intelligences from Gardner’s theory, Sternberg classifies them into two different types of intelligences: analytic (or academic) and practical. These two types of intelligences differ and are defined as follows: Analytic problems tend to have been formulated by other people, be clearly defined, come with all information needed to solve them, have only a single right answer, which can be reached by only a single method, be disembodied from ordinary experience, and have little or no intrinsic interest. Practical problems tend to require problem recognition and formulation, be poorly defined, require information seeking, have various acceptablesolutions, be embedded in and require prior everyday experience, and require motivation and personal involvement. (Neisser et al., 1996, p. 79)

If an individual could solve one or the other of these types of problems well, then that individual would have a high analytic or practical intelligence, respectively. Also, there exist virtuosos, or individuals who are extremely talented in the fine arts, these people would have a high creative intelligence.One reason why Sternberg’s theory has received so much acclaim is that in real-life situations, is has proven itself. For example, Brazilian street children can do the math that they need to know in order to run their street businesses, but they are unable to pass a math class in school (Carraher, Carraher, & Schliemann, 1985). Evidence such as this shows that there are two different types of mathematical intelligence, an academic classroom mathematical intelligence and a street wise practical intelligence.Other theories. In addition to Gardner’s and Sternberg’s theories on multiple intelligences, there are other theories as well, including Thurstone’s and Guilford’s. Both were proponents of multiple intelligences.

Thurstone (1924) stated that “the biological function of intelligence is to protect the organism from bodily risk and to satisfy its wants with the least possible chance of recording failure on the environment” (p. 162). With this in mind, he found several primary mental abilities. As expected, these abilities are those abilities that the individual uses in order to survive and succeed in society. He found this using factor analysis, like Spearman, but Thurstone took the factor analysis a step further and rotated the factors. He arrived at 13 different factors as opposedto Spearman’s one and called these primary mental abilities. These factors included spatial, perceptual, numerical, logical, verbal, memory, arithmetical reasoning, and deductive abilities (Thurstone, 1938). Guilford (1967) found that the structure of intellect was composed of 4 contents, 5 operations, and 6 processes. Each of these was mixed and matched to come up with 120 different combinations of abilities.

There are two distinct schools of thought on the nature of intelligence. The proponents of one general intelligence have a theory that explains the biological reasons for intelligence. Given that they see neural processing speed as the root for intelligence, their theory has an effective causal explanation. On the other hand, the theory of one general intelligence does not encompass all peoples. In the example with the Brazilian street children, they would most likely score poorly on an intelligence test, and be labeled with a low general intelligence. However, they are intelligent enough to be able to do all of the math that they need to know how to do. A drawback to the general intelligence school of thought is that it is heavily dependent on psychometric evaluations. Consequently, it cannot take into account the vast array of different talents that people have.As for multiples intelligences, there are many theorists in that school of thought as well. Some of the theories presented by the proponents of multiple intelligences are excessive and have too many constructs to measure for example, Guilford’s theory. But there are reason able explanations of intelligence put forth by those from the school of multiple intelligences. Gardner’s theory has a very clear causal explanation for intelligence, like the explanation of one general intelligence. But, unfortunately, it is very difficult to pinpoint and confirm Gardner’s hypotheses experimentally, because of the delicacy involved with the human brain. Sternberg’s theory does not have a biological basis to it, and that detracts from its validity. But that may also be its strength. The theory does not focus on the brain and biological functions, but on different social situations.

Therefore, the theory applies to different social situations and environments, as none of the other theories does. But, given that there still is a substantial debate about the nature of intelligence, and no one theory is accepted by all, there is still room for improvement on any given theory.