In the most general sense, intelligence can be defined as levels of cognitive ability. An influential definition, proposed by David Wechsler in 1944, is “the aggregate or global capacity of the individual to act purposefully, to think rationally, and to deal effectively with its environment” (1). Based upon factor-analytical studies, Robert J. Sternberg and others have proposed that there are three main types of intelligence, namely analytical intelligence, practical intelligence and creative intelligence (see: Triarchic theory of intelligence). Other thinkers have since proposed the additional component of emotional intelligence. A standard measurement tool for intelligence is the IQ-score, in which the results of sets of tests are compared to the current average performance of a population.


1. Wechsler, D. (1944). “The measurement of adult intelligence (3rd ed.)“. (p. 3). Baltimore: Williams & Wilkins.