Tests of Intelligence and Academic Achievement
Many psychological assessments also use intelligence or academic achievement as a way to measure the client’s abilities or aptitudes. Reasons for including such tests vary widely. In some cases, the professional needs this information to get a more complete picture of the person’s strengths and weaknesses. In other cases, such measures are used to determine whether the client’s emotional state interferes with his/her ability to learn or think effectively.

Intelligence in the broadest sense refers to adaptive ability. When faced with a difficult problem, can an individual concentrate and bring her ability to bear on solving the problem? When faced with difficult life circumstances, can the individual respond effectively to deal with the situation? It is important to recognize that intelligence is far more than just scores on an intelligence test, it also includes the ability to cope and adapt to real life situations. Some people score poorly on tests but adapt remarkably well to what life throws at them. Others show the opposite pattern, their high IQs and academic credentials do not serve them well in life’s circumstances.

Despite the limitations of intelligence testing, such tests are among the most widely researched, best understood and most useful instruments used today. More is known about the reliability and validity of these measures than of any other class of instruments used in psychological testing.

Wechsler Intelligence Scales (Wechsler Adult Intelligence Scale [WAIS], Wechsler Intelligence Scale for Children [WISC]). Each of these scales is in their third edition (WAIS–III, WISC–III), but earlier versions are used at times. While the adult and child versions differ in details and level of difficulty, both use a similar approach to assess intellectual ability. Each consists of a wide range of sub–tests covering both verbal and performance–based ability. Each such sub–test begins with relatively easy items, and the testing continues until the client can no longer answer the items effectively or correctly. Both the WAIS–III–R and the WISC–III–R yield IQs in the verbal and performance domains, as well as an overall composite called the Full Scale IQ. Research indicates that a number of factors, including verbal ability, perceptual organization, speed, attention/concentration and memory underlie performance on the Wechsler Scales. The more recent versions of the test allow the clinician to individually measure these factors to get a clearer sense of the client’s strengths and weaknesses.

Other Intellectual Measures
A wide variety of other measures are available for measuring intelligence, including the Ravens’ Progressive Matrices, the Test of Nonverbal Intelligence and the Stanford Binet Intelligence Scale (for children). While these tests are not as widely used or as well researched as the Wechsler Scales, they may be used in specific situations depending on the abilities or needs of the client. For example, the Test of Nonverbal Intelligence might be used with individuals who have poor verbal abilities because it does not require spoken or written answers.

Measures Of Academic Achievement
As the name implies, this class of instruments evaluates performance in academic areas. It has sometimes been said that, while intellectual assessment focuses on aptitude (potential), tests of achievement measure how well that aptitude has been applied in acquiring certain academic skills. The most widely used tests of academic achievement are given in public and private school settings and are given in a group format. Additional tests are available for individual administration and are typically used in the clinical setting when the needs of a specific child or adult are being evaluated.

The two most widely administered screening devices are the Woodcock–Johnson Psychoeducation Battery–Revised (WJ–R) and the Wide Range Achievement Test, Version 3 (WRAT–3). Such measures are typically administered and the results are compared with intellectual testing results. In general, significant discrepancies between aptitude (IQ) and achievement are cause to suspect the presence of a learning problem. Many jurisdictions define a learning disability (at least in part) as a significant discrepancy between IQ and achievement coupled with a history of academic difficulty. The size of the discrepancy needed for a diagnosis of learning disability differs across jurisdictions.