THEORIES OF INTELLIGENCE

Charles G.Morris and Albert A.Moisto, Rob Plotnik

Intelligence is a general term referring to the ability or abilities involved in learning and adaptive behavior.

Early theories

Charles Spearman, maintained that intelligence is quite general, or spring, of mental energy that flows through every action. Spearman believed that people who are bright in one area are often bright in other areas as well. In 1904, Charles Spearman reported that he had measured intelligence in an objective way. He was one of the first to use the psychometric approach.

Spearman reasoned that by measuring related cognitive factors he would have an objective measure of intelligence. This idea led to his two-factor theory of intelligence.

Spearman’s two-factor theory says that intelligence has two factors :

1. a general mental ability factors, g, which represents what different cognitive tasks  have in common

2. many specific factors, s, which include specific mental abilities (mathematical, mechanical, or verbal skills)

Spearman believed that factor g, or general mental ability, represented a person’s mental energy. Today, factor g is defined and measured by a person’s performance on various and related cognitive abilities. In other words, modern intelligence tests have essentially changed or transformed Spearman’s g into an objective score, which is commonly known as the IQ score. Today, many psychologist believe that g, as represented by IQ scores, is a good measure of a person’s general intelligence. Many psychologist believe that g is the definition of general intelligence, which can be measured by an IQ test and represented by an IQ score.

Advantages and disadvantages

Advantages

G that it can be objectively defined and measured by an IQ test, which gives a single IQ score that is presumed to reflect a person’s general intelligence. Another advantage is that g is a good predictor of performance in academic settings and has some success in predicting performance in certain careers.

Disadvantages

Spearman’s g is the continuing debate over whether it is the best measure of intelligence. A second disadvantage of g is that is focuses on cognitive abilities but neglects motor, perceptual, musical, practical, and creative abilities, which some believe indicate other kinds of intelligence. A third disadvantage is that g and its focus on cognitive abilities is popular in western cultures but not in many Asian and African cultures, where being intelligent includes other abilities, such as how one relates to and understands other.

The American psychologist L. L Thurstone disagreed with Spearman. Thurstone argued that intelligence is composed of seven distinct kinds of mental abilities : spatial ability, memory, perceptual speed, word fluently, numerical ability, reasoning, and verbal meaning. Thurstone believed that these abilities are relatively independent of one another. Thus, a person with exceptional spatial ability might lack word fluency. To Thurstone, these primary mental abilities, taken together, make up general intelligence.

R. B Cattel (1971) identified just two clusters of mental abilities. The first cluster : crystallized intelligence, includes abilities duch as reasoning, and verbal and numerical skills. Cattel’s second cluster of abilities : fluid intelligence, is made up of skills such as spatial and visual imagery, awareness of visual details, and a capacity for rote memory. Scores on test of fluid intelligence are much less influenced by experience and education.

Contemporary theorists

Psychologist Robert Stenberg defined intelligence by analyzing three kinds of reasoning processes that people use in solving problems. Stenberg calls his approach the triarchic theory of intelligence. Robert Stenberg’s triarchic theory of intelligence concludes that human intelligence encompasses a much broader variety of skills than described by earlier theorists and that skills necessary for effective performance in the world are just as important as the more limited skills assessed by traditional intelligence tests.

Stenberg’s triarchic theory says that intelligence can be divided into three different kinds of reasoning processes (triarchic means three). The first is using analytical or logical thinking skills that are measured by traditional intelligence tests. The second is using problem-solving skills that require creative thinking and the ability to learn from experience. The third is using practical thinking skills that help a person adjust to, and cope with, his or her socioculutural environment.

Advantages and disadvantages

Advantage

Stenberg’s triarchic theory of intelligence is that it doesn’t limit the definition of intelligence to cognitive abilities. Instead, Stenberg’s theory evaluates a person’s intelligence by measuring three different kinds of reasoning processes and how they contribute to a person’s success.

Disadvantage

Sternberg’s research and tests for measuring his proposed three kinds of reasoning processes have so far been critized as providing little support for his triarchic theory.

 Head size and intelligence

Francis Galton noticed that intelligent people often had intelligent relatives and concluded that intelligence was, to a large extent, biological or inherited. Galton measured people’s heads and recorded the speed of their reactions to various sensory stimuli. However, his measures proved to be poorly related to intelligence or academic achievement. Galton switched gears and tried to correlate head size with students grade point average.

Brain size and intelligence

Paul Broca claimed that there was a relationship between size of brain and intelligence, with larger brains indicating more intelligence. However, a later re-analysis of Broca’s data indicated that measures of brain size proved to be unreliable and poorly correlated with intelligence. However, such correlations indicate only that a relationship exists, correlations cannot tell us whether bigger brains lead to increased intelligence or whether more cognitive activity leads to bigger brains. These medium-sized correlations indicate a positive relationship between brain size and intelligence but are too low to have practical value in actually predicting an individual’s intelligence.

Brain size and achievement

Early researches were reluctant to give up the idea that bigger brains were better. They looked for a relationship between brain size and personal achievement, another measure of intelligence. There is enormous variation in brain size and achievement. Notice that Nobel Prize-winner Einstein’s brain (1,230 grams) was slightky below average weight and that two famous authors, poet Walt Whitman (1,200 grams) and novelist Anatole France (1,000) grams, achieved literary fame with brains about half the weight of Jonathan Swift’s (2,000 grams), one of the heaviest on record.

Brain size, sex differences, and intelligence

Still believing that bigger brains are better, some researches claimed that women had lower IQ scores than men because women’ brains weight about 10% less than men’s. however, a recent study of over 4,000 women and 6,000 men reported that there was little or no difference in intelligence between men and women. Researches concluded that the larger size of men’s brains does not result in higher IQs.