Achievement, Aptitude, and Ability Tests

Theoretical Distinction

Achievement tests are designed to assess the extent to which a person has developed a specific motor skill or [Page 1393]learned a specific body of knowledge. Typically, an achievement test is administered following a period of instruction designed to teach the motor or cognitive skill to be examined. The prototypical achievement test is the periodic classroom exam that is administered to determine how much the student has learned. Other examples include the written and driving tests taken to secure a driver's license, the Scholastic Assessment Test (SAT) and American College Test (ACT) taken by high school students contemplating college, and the Graduate Records Examination (GRE) taken by college students who want to go to graduate school.

Theoretically, the purpose of the achievement test is descriptive—to measure the extent to which an examinee has mastered a motor skill or area of knowledge. In practice, however, achievement test results often are interpreted as an indicator of future performance. For example, while achievement tests such as the SAT and GRE evaluate the knowledge examinees have accrued as a result of their educational experiences, scores on those tests are used to predict the likelihood of success in more advanced and challenging programs of study. This common practice confounds the performance assessment (i.e., descriptive) function of achievement tests with the prediction goals of aptitude tests.

Many achievement and aptitude tests are very similar in appearance, but the primary purpose of aptitude tests is prediction. They are designed to obtain information that can be used in predicting some aspect of the person's future behavior. Aptitude tests assess the examinee's ability to learn both cognitive and motor skills. Often, scores on a broadly based test of verbal comprehension are used to predict the examinee's potential to learn (and use) new cognitive skills. In fact, the most common use of aptitude tests is to predict future performance in an educational program or occupational setting. However, some aptitude tests measure motor skills (e.g., eye-hand coordination or the time it takes to run a 40-yard dash). Scores on aptitude tests such as these are used to predict the examinee's ability to learn (and use) desirable motor skills.

The distinction between aptitude and ability tests is subtle, and many psychologists and test publishers use the terms interchangeably. In general, however, ability tests assess cognitive and motor skill sets that have been acquired over a long period of time and that are not attributable to any specific program of instruction. For example, intelligence tests such as the Wechsler Adult Intelligence Scale—Third Edition (WAIS-III) and the Stanford-Binet Intelligence Scales, Fifth Edition (SB5) measure verbal comprehension, working memory, perceptual organization, and processing speed. These abilities are not the result of any specific program of instruction. Instead, they are believed to be a function of the person's native ability to learn from life experiences. Ability tests are descriptive in that they assess people's knowledge and skills, but they are also predictive because they measure qualities that are presumed to influence the person's ability to learn new skills and to solve novel problems.

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