The Nature and Purpose of Intelligence, Aptitude, and Special Aptitude Tests

In general terms, various forms of psychological tests have been employed for the purpose of measuring “differences between individuals or between the reactions of the same individual under different circumstances” (Anastasi & Urbina, 1997, p. 2). More specifically, the measurement of ability represents one of the most widespread applications of psychology and psychometrics in everyday life. These assessments of ability range from instruments that test general mental ability – referred to as intelligence tests – to those that tap specific abilities – referred to as aptitude and special aptitude tests.

Intelligence Tests

General intelligence testing represents both one of the early applications of systematic psychometric testing and one of the most controversial issues is psychology. Fundamentally, intelligence tests constitute measures of general aptitude whereby the resulting scores represent a composite of cognitive abilities which can be used to forecast achievement and success for a wide range of situations. In a sense, these tests are considered measures of an individual’s learning potential. Individual intelligence testing can trace its origins to the early work of Galton, Wundt, Cattell, Kraepelin and Ebbinghouse in the late nineteenth and early twentieth centuries.

The first widely used intelligence scale was developed in 1905 by Alfred Binet and Theodore Simon specifically to “identify children who could not profit significantly from schooling” (Walsh & Betz, 2001). The original scales (the Binet-Simon scales) consisted of a set of 30 problems varying from very simple sensorimotor tasks to more difficult problems involving judgment and reasoning and included a comparative age-linked scale of intelligence.

In subsequent years, these original scales underwent several revisions, yielding the updated Stanford-Binet scales and the popular concept of the IQ (intelligence quotient, or ratio between mental age and chronological age). Although the underlying philosophy of the test – excluding slower children from educational opportunity – has changed markedly, this scale represents the beginning of widespread intelligence testing and the main model for subsequent scales of this nature. Psychologists in the United States emphasized a utilitarian focus, utilizing intelligences tests for such purposes as classifying immigrants and Army recruits (Boake, 2002).

Beginning in 1938, David Wechsler designed a series of general intelligence measures composed of items appropriate for testing a wide range of ages. The primary impetus for the development of this series of tests was the recognition that the Stanford-Binet tests were designed primarily for children and thus did not provide an adequate measure of adult intelligence. These tests also underwent various revisions over the years, including the development of a version for children. The current version of the test – the Wechsler Adult Intelligence Scale-IV (WAIS-IV) - represents the most widely used individual test of adult intelligence. WAIS-V is currently under development. Additionally, various alternative forms of general intelligence tests have been designed for special populations, including, individuals with sensory limitations (e.g., deaf individuals) or physical limitations (e.g., paralyzed individuals), individuals with language limitations (e.g., non-English speaking individuals), individuals from other cultures, individuals with learning disabilities, and individuals with brain damage.

Measures in the category of intelligence tests have been proposed to function as assessments of general mental or intellectual ability, as distinguishable from the measures of special ability. In this way, the items on intelligence test represent attempts to assess individual differences in the effects of experiences common to most individuals, particularly in Western culture. It is assumed that, when exposed to the same experiences, individuals with higher intelligence benefit more from those experiences than persons of lower intelligence.

Consequently, to the extent that test makers are successful, scores on intelligence tests should be influenced more by differences in basic mental ability than by variations in experience. Typically, these intelligence tests provide an overall score, such as the common IQ, and various sub-test scores which indicate ability along more specific criteria. As such, they are useful in a variety of educational, clinical and occupational settings. Currently, “the classification of children with reference to their ability to profit from different types of school instruction, the identification of outstandingly slow or fast learners, the educational and occupational counseling of high school and college students, and the selection of applicants for professional schools” represent the variety of ways in which tests of this nature are implemented (Anastasi & Urbina, 1997, p. 3).

Aptitude and Special Aptitude Tests

Because general intelligence tests measure a broader array of abilities, they tend to be moderately effective in predicting a wide range of performance criteria, especially for broad criteria that also represent a complex product of many variables (i.e., overall intellectual potential). In contrast, narrower, more specialized tests designed to evaluate particular abilities will generally tend to measure a specified variable more precisely and to predict a narrower range of criteria more accurately. While intelligence tests are used to predict future performance generally and broadly, aptitude tests evaluate the potential for learning and predict potential is a more limited performance area (e.g., academic or occupational success). As such, they are often employed to evaluate the “potential to profit from a course of training” (Kaplan & Saccuzzo, 2018, p. 340).

Aptitude tests measure one or more clearly defined and relatively homogeneous segments of ability and generally can be divided into type types – single aptitude and multiple aptitude test batteries. A single aptitude test appraises one specific ability, while a multiple aptitude test battery provides a profile of scores for a number of related aptitudes. These tests were developed from the early work of Spearman and Thurstone involving the factor analysis of the more global measures of mental abilities. Additionally, special aptitude tests represent very specific assessment measures, such as clerical skill, mechanical ability, manual dexterity, artistic ability, and musical talent.

In the field of applied psychology, the assessment of aptitude has two major applications – the evaluation of scholastic aptitude and the evaluation of aptitudes necessary for successful performance in different occupations. These measures are used extensively in the counseling, selection, and placement of applicants in various educational programs and/or for professional opportunities.

References

Anastasi, A. & Urbana, S. (1997). Psychological testing (7th ed.). New York, NY: Prentice Hall.

Boake, C. (2002). From the Binet-Simon to the Wechsler-Bellevue: Tracing the history of intelligence testing. Journal of Clinical and Experimental Neuropsychology, 24, 383-405.

Kaplan, R. M. & Saccuzzo, D. P. (2018). Psychological testing: Principles, applications and issues, (9th ed.). Boston, MA: Cengage Learning.

Walsh, W. B. & Betz, N. E. (2001). Tests and assessment (4th ed.). Upper Saddle River, NJ: Prentice Hall.