Psychological testing measures an individual's performance at a specific point in time. Psychological tests can't predict future or innate potential. Psychological testing is not a single test or even a single type of test. It encompasses a whole body of dozens of research-backed tests and procedures of assessing specific aspects of a person's psychological makeup.
Cognitive functions can be defined as cerebral activities that lead to knowledge, including all means and mechanisms of acquiring information. Cognitive functions encompass reasoning, memory, attention, and language and lead directly to the attainment of information and, thus, knowledge.

The clinical interview is a core component of any psychological testing. All assessments begin with a clinical interview, a review of medical records, as well as any other pertinent data. This interview provides an opportunity to gather important background and family data. Clinical interviews typically last from 1 to 2 hours in length.

Cognitive assessments may include assessment of IQ or level of intelligence, perceptual abilities, verbal and non-verbal skills, attention and processing or memory abilities. Typically, cognitive ability tests cover some or all of the following categories: numerical, verbal, abstract, spatial, and mechanical reasoning. Questions can take many different forms and cover varying degrees of difficulty, depending on the type of ability being assessed.

The most commonly administered IQ test is called the Wechsler Adult Intelligence Scale IV (WAIS-IV) and is appropriate for any individual aged 16 or older. Depending on age, a child can be administered the Wechsler Intelligence Scale for Children IV (WISC-IV), or the Wechsler Preschool and Primary Scale of Intelligence IV (WPPSI-IV).

Many kinds of psychological tests are available for specific areas, such as aptitude or achievement in school, career or work counseling, management skills, and career planning.

Psychological Assessments