Intelligence can be defined as a person’s capacity to (1) acquire knowledge (i.e. learn and understand), (2) apply knowledge (solve problems), and (3) engage in abstract reasoning. While IQ scores do have high predictive validity for individual differences in school achievement, they have little ability to predict individual success or career progression.
IQ tests were originally used to detect children of lower intelligence, in order to place them in special education programs. Tests of IQ tests are designed to compare a child’s intelligence to what his or her intelligence “should be” as compared to the child’s age. If the child was significantly “smarter” than a “normal” child of his or her age, the child was given a higher score, and if the child scored lower than expected for a child of his or her age, the child was given a lower IQ score.
The only clinical use of IQ tests today is to detect mild mental retardation. Mental Retardation (MR) is characterized by significantly impaired cognitive functioning and has historically been defined as an IQscore less than 70.
In early childhood mild mental retardation (IQ 50–69) may not be identified until the child begins school. It may take expert assessment to distinguish mild mental retardation from conditions such as Learning Disability or emotional and / or behavioral disorders. As individuals with mild mental retardation reach adulthood, many learn to live independently and maintain gainful employment.