IQ tests measure cognitive abilities. These tests are used for many purposes, including the diagnosis of learning difficulties and school and occupational placement. Over the years, intelligence tests have evolved. Today, the most commonly used tests are the Wechsler Scales and the Stanford-Binet Intelligence Scale.
Definition
IQ stands for intelligence quotient. This term originally referred to an individual's intellectual abilities in relation to his chronological age. Today these tests continue to provide an overall IQ score, or measure of cognitive ability, but they no longer represent the ratio between mental and chronological age. Instead, they measure an individual's ability level in relation to his peers.
History
As described by Duane and Sydney Schultz in "A History of Modern Psychology," the movement toward measuring mental ability in psychology began in the early 1900s. Alfred Binet, a French psychologist, developed a scale to measure intelligence in schoolchildren. In conjunction with colleague Lewis Terman, an American psychologist at Stanford University, Binet developed the Stanford-Binet test, and the concept of intelligence quotient was introduced. It denoted the ratio of mental age, or intelligence, and chronological age. In other words, the ratio determined whether a child was performing above or below what was expected for his age.
Wechsler Scales
Although many other scales have been developed through the years, the introduction of the Wechsler scales was critical to today's understanding of IQ tests. David Wechsler was an army psychologist during World War I, using intelligence tests to place soldiers in job assignments. Using these tests, which included the Stanford Binet, he developed his own intelligence scales for adults and children. The comprehensiveness and easy use of these scales has made them popular and widespread in the field of psychology.
Purpose of IQ Tests
As noted by Gary Groth-Marnat in the "Handbook of Psychological Assessment," the intent of the IQ test is to provide information about cognitive strengths and weaknesses. They measure various abilities such as verbal knowledge, speed of processing, numerical abilities and perceptual knowledge. These tests can be used to measure change in intelligence or ability over time and can be useful in predicting future ability.
Commonly Used IQ Tests
Several tests measure intelligence, but only a few are commonly used. The Wechsler scales, which include the Wechsler Adult Scale of Intelligence, the Wechsler Intelligence Scale for Children and the Wechsler Preschool and Primary Intelligence Scale, are commonly used, along with the Stanford-Binet Intelligence Scale. Other abbreviated scales or overall measures of intelligence are used, depending on the client.
References
- "A History of Modern Psychology, Ninth Edition"; Duane P. Schultz & Sydney Ellen Schultz; 2008
- "Handbook of Psychological Assessment, Fourth Edition"; Gary Groth-Marnat, 2003
