For years psychologists have tried to understand the elusive concept of intelligence or a general ability that would define and evaluate people. Common as the word may sound, it has been difficult for the researchers, psychologists, and the philosophers to agree upon a single definition for the term.
Most people would agree that intelligence is an ability to comprehend and learn from an experience. It allows the person to conduct his day-to-day tasks, use language, and solve problems that would define his adaptability in the world.
It is commonly accepted that each person is born with his set of distinct abilities or intellectual potential. Society may help mold it, but ultimately a person is shaped by his different potentials. The question, however, remains whether intelligence is linked to a single general mental ability or is it composed of distinct multiple abilities.
Spearman's g Factor
One of the key theories for explaining the concept of human intelligence was coined by a British psychologist, Charles Spearman at the turn of this century in an article published by him on intelligence.
His theory was based on the observation that individuals who scored highly in one test also seemed to display high scores across all tests of mental ability. This is in contrast to people with low scores in a test who fared badly across others as well. He came to the conclusion that all theories of mental ability were positively correlated.
Here correlation is the statistical relation between two variables, and they reflected the influence of a dominant factor which he termed the general factor or 'g'. This factor was extracted using the method of factor analysis.
This widely accepted general factor seems to explain most differences in the mental tests regardless of the ability that the test has to assess. So people who have high scores in mathematical ability would score high in a language test as well.
For different tests, the mental abilities that were tested varied, thus they reflected the 'g' factor at varying degrees. Thus, a battery of tests is required to judge a person's 'g' factor.
Not only does the general factor point out at individual differences, it also provides an insight on intelligence in daily life. It can be associated to smart reasoning, problem solving, and quick learning in everyday life.
Furthermore, this factor analytic research has confirmed a hierarchical model of mental abilities with 'g' factor at the top. Specific aptitudes like verbal ability, memory, and mathematical reasoning follow the 'g' factor and at the end are the skills derived by particular profession or job.
Biological Aspect of the g Factor
Spearman's general factor has many biological correlations. Researchers have discovered that several brain attributes can be linked to general intelligence. The brain size and the peripheral nerve conduction velocity seemed to be correlated to 'g'. For example, brains of brighter people seemed to expend less energy than their less-abled counterparts.
One of the other significant factors is the inheritability of the general factor. The genetic endowments along with an individual's environment shape the differences among individuals. Along with these, measures of 'g' seem to positively correlate with the social measures of success in life, like academic achievement, college, career, etc.
The controversy surrounding the general intelligence factor have been based on improper use of mental tests. Critics argue that these IQ tests affect the capability of a person. Intelligence theorists like Howard Gardner and British philosopher Philip Kitcher have argued that there can be no single measure of intellectual ability.
They propounded the theory of multiple intelligence. Countless studies have failed to show the consistency of performances across tests.
As scientists continue to debate the existence of the 'g' factor, it is impossible to disregard the fact that the mental abilities among individuals vary. Recognizing this can help the society draw better solutions to address the different intelligence levels of people.