Intelligence Quotient (IQ)

Intelligence is a construct that has been proposed by psychologists to underlie much of human behavior and is a significant factor contributing to an individual's ability to do some things more or less well. Most would agree that some children are better at math or language arts than others, or that some hockey players or musicians are gifted in comparison to their peers. It might be argued that some individuals are born that way, whereas others have the benefit of good environments and learning opportunities that can build on their basic abilities. The intelligence test, and resulting intelligence quotient or IQ, is a means for assessing and measuring intelligence, with the results often used to classify or select persons or predict such outcomes as school achievement.

Both the construct of intelligence and its measurement are not new, and both existed well before the advent of psychological science. Historians have traced the forerunner of current cognitive ability and achievement assessment to more than 2000 years B.C. Although intelligence has been studied in a number of ways, from an early emphasis on sensory processes to the more current attention given to brain-imaging techniques, the mainstay in the study and assessment of intelligence has been the IQ test. Psychologists not only assess intelligence but also study how intelligence is expressed; what causes it; and how it contributes to understanding, explaining, predicting, and even changing human behavior.

Despite intelligence being a much studied area of psychology, there is still considerable controversy and emotion regarding the use of the IQ and intelligence tests and the results gleaned from them in such contexts as schools and industry to describe both individuals and groups. Given continued advances in the theories of intelligence and cognitive assessment instruments, the issue appears to be less with the constructs and the tests used to measure it, and more with how this information is or can be used.