Evolution of intelligence: and approach to its assessment.

The goal was to suggest a meaningful approach to the assessment of intelligence which may be used, for example, in correlational studies with measures of encephalization. Suggesting, as others have done, that species comparisons based on quantitative inherently confound intellective with nonintellective abilities, the present approach described a hierarchy of 8 basic levels of qualitatively different intellective (learning) abilities. The levels range from habituation to complex concepts. Practical procedures and strategies which increase the precision of the scale were described.