The term "cognition" refers to all processes by which the sensory input is transformed, reduced, elaborated, stored, recovered, and used. It is concerned with these processes even when they operate in the absence of relevant stimulation, as in images and hallucinations. Such terms as sensation. perception. imagery. retention. recall. problem-solving. and thinking. among others. refer to hypothetical stages or aspects of cognition.

p. 4 - Cognitive Psychology, 1967