The underlying goal of general ability tests is to assess potential candidates in terms of their overall intellectual potential and build a profile of their individual strengths and weaknesses. There is a body of research to suggest that cognitive ability testing is a strong predictor of job performance and that the validity of this predictor rises as the complexity of the job rises. 

The main types of ability test used in selection are:

• Tests of General or Global Ability (also called "g", intelligence, IQ)
• Tests of Specific Cognitive abilities (Abstract Reasoning, Verbal Reasoning, Numerical Reasoning)
• Tests of Psychomotor abilities and specific aptitudes (vision, hearing, motor dexterity, artistic ability, mechanical ability, management potential, leadership potential etc.)

Tests of General/Global ability attempt to measure a person's ability to problem solve, analyse, understand and adapt to new situations or challenges. They usually produce an IQ score or measure of 'g'. In the workplace setting tests of this type are often "short versions" with the emphasis on gaining a better understanding of a person's general strengths and weaknesses in relation to other graduates, rather than deriving an IQ type score.

Tests of specific cognitive & psychomotor abilities attempt to measure the depth and nature of particular strengths and weaknesses in subject or job related areas. Typically these involve high level cognitive processing, complex problem solving, analytical reasoning, verbal reasoning, abstract reasoning and information checking. In some instances tests may extend to visual acuity, motor dexterity, mechanical reasoning and other psychomotor domains. The choice of test is largely dependent upon the context and nature of the role.