Intelligence testing is used for a number of purposes, particularly in the educational system. Intelligence test scores are a major criteria in determining if a child is put in gifted and talented classes. Likewise, intelligence tests are used to determine if a child needs special education services. For those children suspected of having learning disabilities, the IQ-academic achievement discrepancy model is used most often. This looks at a child's IQ score. If there is a big difference between a child's academic potential as indicated by intelligence scores and the child's actual school achievement, learning disabilities are considered the likely cause. However, the difficulty in relying on IQ scores to determine learning disabilities is that the test score will likely be affected by the child's learning disability and therefore not accurately measure a child's true potential.
Intelligence testing generally deals only with certain elements of intelligence, such as linguistic, logical, and some spatial types of skills. For instance, the Wechsler Intelligence Scale for Children-Revised or WISC-R, is made up of verbal and performance sections. In the verbal section, vocabulary, specific knowledge, expressive language and memory skills are assessed. In the performance part of the WISC-R, visual-spatial abilities, fine motor and perceptual skills are scored. However, many experts, most notably psychologist Howard Gardner, have argued that there are many more aspects to intelligence than these skills, such as musical, kinesthetic (bodily), spatial, linguistic, interpersonal and intrapersonal skills.
One significant issue with intelligence testing is unreliability. A person's score can vary as much as 15 points from test to test. S.J. Gould in "The Mismeasure of Man" cited the importance of the tester on the outcome of the intelligence test results, noting a study of 99 school psychologists who were given the same IQ test to score. The scores ranged from 63 to 117.
Another major concern with intelligence testing is that they are biased against various cultural, racial or socioeconomic groups. Those who do not respond in an expected way or by the way of the majority group do not score as well. Another concern is that the tests measure test-taking skills more than intelligence.
Perhaps the largest issue with intelligence testing is that since there is not any one established set of criteria for intelligence or even a coherent definition, it cannot be adequately measured. Intelligence can not be measured and plotted objectively like a child's physical growth.