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a2zpsychology.com  >  Psychology Guide  >  Basic Concepts  >  Intelligence

People differ in the speed with which they learn things and how well and how long they remember ideas. They also differ in their ability to understand ideas and to use their knowledge in solving problems. For example, some people can solve mathematical problems rapidly. Others quickly understand how machines work. Still others can easily learn new words or a foreign language. All these abilities--and many more--are factors in what is called intelligence. 

What is intelligence? 

There is no universally accepted definition of the word intelligence. But a person is considered intelligent to the degree that he or she has the abilities mentioned above. Although such abilities are somewhat related, a person may be high in some and low in others. A person who can memorize names and dates may have trouble with long division. Another who has creative talent in art or music or has inventive ability may lack other abilities associated with intelligence. Although creativity and intelligence are known to be related, some people of above-average intelligence do poorly when faced with problems that are new to them. 

Intelligence is sometimes regarded as a combination of qualities that lead to success in school. But some abilities, such as mechanical skill, are not used much in school. As a result, tests designed to measure intelligence include few questions that deal with mechanical skill. In addition, IQ (intelligence quotient) tests do not emphasize originality. Thus, they provide an incomplete picture of the many factors involved in intelligence.

Where intelligence comes from. 

A person's intelligence depends on heredity and environment. Every person is born with a certain mental capacity that influences how intelligent he or she will be as an adult. The development of this capacity is influenced by the person's background. Youngsters who are severely undernourished in infancy may be unable to develop their natural abilities. Similarly, children who are beaten or ridiculed by their parents may become so upset that their intellectual talents remain underdeveloped. Many children who face discrimination because of their race or nationality or a physical handicap also fail to develop their capacities to the fullest extent possible. 

Controversy over intelligence. 

Scientists have long disagreed about the relative importance of heredity and environment in determining intelligence. In the 1960's, investigators found that children who had completed special preschool programmes experienced IQ score gains of as much as 15 points. Other studies have shown that children have suffered in intellectual development if they have been severely neglected or have received too little mental stimulation. Therefore, some psychologists emphasize the importance of the environment in determining IQ. 

Other psychologists, however, attach greater weight to heredity. They note that identical twins, who have exactly the same genes, have nearly identical IQ's. On the other hand, fraternal twins, who are about as genetically similar as ordinary brothers and sisters, are not as similar in IQ as identical twins. In addition, identical twins who are adopted into different families as infants still have similar IQ's as adults. 

As a result, most psychologists conclude that both heredity and environment are important in determining intelligence, but that each limits the other. That is, they believe a person's genetic potential for intelligence can only be reached in a favourable environment. But they also believe that environment, no matter how favourable, cannot create a potential that is not present genetically.