At the very heart of cognitive psychology is the idea of information processing.
Cognitive psychology sees the individual as a processor of information, in much the same way that a computer takes in information and follows a program to produce an output.
Cognitive psychology compares the human mind to a computer, suggesting that we too are information processors and that it is possible and desirable to study the internal mental / mediational processes that lie between the stimuli (in our environment) and the response we make.