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Assessment Instruments: Intelligence Tests

Margaret V. Austin, Ph.D., edited by C. E. Zupanick, Psy.D.

Assessment instruments: Psychological tests of intelligence, academic achievement, and daily functioning

Psychological testing is a key component of a comprehensive ADHD assessment. A standard set of tests are routinely used. Additional tests may be added depending upon initial findings. Usual tests include intelligence tests, achievement tests, and tests of daily functioning. This can include symptom checklists; tests of attention; tests of executive functioning; memory tests; and personality tests. Experts suggest that intelligence has a minimum of two components:

1. the ability to adapt to changing circumstances; and,
2. the ability to learn from previous experience.

paper and penMost likely, intelligence has more than two components. More elaborate theories are evolving. No matter the components, intelligence is thought to be some combination of our inherited, family genetics; and the influence of the world around us (our environment). Most professionals believe that each of us has an inherited intellectual capacity. Whether or not we realize that potential depends on many factors. This includes the available resources; our own efforts; and our motivation.

Over the last decade or so, researchers have learned that our environment has a more powerful influence than was once thought. The word "environment" is used to mean our experiences in the world around us. Research has demonstrated that these experiences can actually cause physiological changes in the brain. Thus, while the environment was once thought to take a back seat to the influence of biology, we now know that it is a bi-directional relationship. The environment can cause changes to our biology. Therefore, it is possible that intelligence is more fluid than previously believed. This tension between the causal relationship of our biology, and our life experiences, is often called the nature-nurture debate. The interested reader can learn a great deal more about this debate through a simple Internet search.

When clinicians administer intelligence tests, they are looking for behavioral and cognitive patterns that are consistent with specific disorders. It is important to note that people with ADHD do not do as well as their peers during intelligence tests. These tests require sustained mental effort. In addition, the structure of most intelligence tests can limit the success of a child with ADHD. Many tests do not allow the examiner to repeat instructions or modify administration rules to accommodate the special needs of some children. Individuals with ADHD often perform poorly on tests that require fast speed, extended focus, and strong working memory skills. Experienced professionals are aware of this tendency and combine the results of these tests with the results of other evaluation techniques. This combination is designed to yield a more accurate assessment of intellectual functioning. The following is a partial list of commonly used tests in each category. Links to information about these assessment tools can be found in the Resource List.

Intelligence Tests

The Weschler Intelligence Scale for Children (WISC)

The Weschler Intelligence Scale for Children (WISC) was originally developed in 1949. Since then, it has been revised several times. It is probably the most commonly used intelligence test for children. A preschool version of the test has also been developed (the WPPSI). Each Weschler test evaluates two primary areas: verbal skills and performance skills. Scores in both of these areas are used to arrive at a combined score (the so-called IQ score). IQ scores can be used to compare an individual's score with their peers (the average IQ score is 100). These tests assess factual knowledge, spatial skills, logical thinking, and mathematical abilities. The WISC is designed for use with children between 6 and 16 years of age.


This test evaluates a child's knowledge of vocabulary, comprehension skills (i.e., understanding language), and visual pattern recognition. Stanford-Binet scores allow testers to determine at what age a typical student could answer a specific question. People performing at the average level for their age group would have an IQ score of 100.