Psychological testing has become a widely accepted, and for the most part trusted, aspect of our modern way of life. Psychological assessments are now commonly used in areas such as student placements (via aptitude and intelligence testing), part of standard business interview and hiring practices (occupational and achievement assessment), and in the medical field (through the use of neuropsychological assessments), to objectively determine specific functional and performance levels of the individuals under evaluation. Understanding the basic facets of psychological assessments, such as the assumptions upon which they are founded, the broad based categories of psychological evaluations, and the concepts upon which they rely in order to ensure that they present results that truly measure the functional and/or performance areas they are supposed to measure, is essential for those that engage in the construction and analysis of these tools.

The term “test” as it relates to psychological assessment has a much broader meaning than the standard layman’s term, which is found in the English language dictionary. According to the popular Merriam-Webster’s Dictionary, the term can essentially be defined as “a critical examination, observation, or evaluation,” and “something (as a series of questions or exercises) for measuring the skill, knowledge, intelligence, capacities, or aptitudes of an individual or group.” Psychological evaluations however, narrow the definition to a procedure or instrument that is designed to obtain information which is measurable and quantifiable with regard to cognitive, behavioral and/or functional aspects through the application of standardized procedures and processes. So the purpose of psychological assessments is to provide a reliable, objective, standardized method for measuring a particular area of individual performance or behavior.

Psychological Assessment Assumptions


During the process of both structuring psychological and administering evaluation tools, certain assumptions have to be made with regard to the individuals and population, which is being tested. These assumptions are integrated into the basis upon which the tests are built. If the assumptions are found not to be true, it is possible that the test results likewise are invalid.  First, it is assumed that a test will measure exactly what it is supposed to measure. This statement of assumption refers to the validity of the tool. Hence, if the objective of an assessment tool is to measure intelligence, however includes a high degree of dependency upon a specific culture, language, or other factor that introduces bias, then score validity is questionable, especially if administered to individuals outside the environment in within which the assessment tool was developed.


Another assumption is that the assessment score for an individual that has taken the test will remain the same, for the most part, over time. This assumption of reliability applies primarily to the state of the aspect under evaluation at the time the instrument is administered. So again using intelligence assessments as an example, if an individual is administered an intelligence assessment at 18 years old and again at 30 years old, we would expect the resultant scores to be about the same (otherwise the test would be measuring knowledge or other criteria instead of only intelligence quotient).

Truth and Accuracy

It is also assumed that individuals administered a psychological evaluation will accurately and truthfully report or answer each question about them, rather than answering with what they think is socially acceptable or the “right” answer. Similar to the previous assumption, it is expected that the individuals being evaluated will respond in accordance with their actual feelings, rather than being influenced by what they believe meets the expectation of the assessment creator or administrator. Finally, it is also assumed that the test score for each individual that is administered a psychological test is an accurate measurement of the psychological aspects being analyzed about that particular individual.

Psychological Test Categories

Personality Tests

               Personality tests are designed to measure and report on the specific personality characteristics of an individual. These tests are commonly used to assess whether or not an individual possess the character traits desired within a particular group, and/or if an individual has particular tendencies as components of their behavior (for example, a tendency to be compulsive).

Occupational Tests

Occupational or career/vocational tests are similar in many ways to personality tests however they are designed to apply directly to the workplace, used for pre-screening potential candidates for hire, as well as determining where individual employees may be best suited to work within an organization.

Neuropsychological Tests

Neuropsychological tests examine mechanics of a subject’s cognitive functioning such as the ability to reason and think. This type of test is most often administered to individuals that may have suffered from some form of neurological trauma such as a stroke or severe injury to the head.

Intelligence Tests

Intelligence tests aim to provide an objective, unbiased measurement of pure intellectual capability, including the ability to solve problems, reason, and understand and make sense of the world around them. Valid intelligence tests aim to quantify intelligence aside from knowledge, culture, language and other external factors that are often assumed in society to be indicators of intelligence. Intelligence tests are quite often administered in educational settings such as prior to elementary school enrollment.

Aptitude Tests

Aptitude and/or achievement tests are designed to measure performance either of the individual being tested or to determine the effectiveness of a program, or assessment of a group. Aptitude tests are commonly used to measure student performance in grasping educational concepts, interests and attitudes, measuring the effectiveness of training programs, and also to measure trends and/or progress of subjects or groups within particular programs.

Reliability vs. Validity

Reliability and validity, are very different yet important aspects of psychological testing. Reliability refers to a test instrument providing the same result when a test is administered and then re-administered. In contrast, validity refers to how well the test measures what it is supposed to measure, the accuracy of the test results, and how well the test predicts performance in the areas of focus. So if a test is not reliable, test results will vary outside of the margin of acceptable error for the given test whereas if a test is not valid, it measures aspects other than what it is intended to measure.


Psychological testing is used to provide test administrators and those that take the tests with valuable insight into psychological performance, behavior, and function. When properly designed, psychological tests can deliver valid, reliable information that clinical, educational and occupational professionals can use to effectively and accurately evaluate individual characteristics and/or state.