Intelligence

The ability to understand concepts and to reason them out. Intelligence can also be considered as having 3 separate forms: abstract (understanding ideas and symbols); practical (aptitude in dealing with practical problems such as repairing machinery); and social (coping reasonably and wisely with human relationships). Intelligence increases up to the age of about 6 years and then stabilizes. Intelligence quotient (IQ), as measured by intelligence tests, continues to increase to about the age of 26, stays the same until about the age of 40, and then gradually declines. Intelligence is partly inherited, although environment also plays a major part, as does physical health and personality. Extremes of intelligence occur in learning difficulties (defined by a low IQ) and in the gifted (defined by scores over 140).