In the renaissance of cognitive psychology, and psychologists accepting a familiar parallel between man and computer, what were the various trends that culminated in the popularity of the "information processing theory?"
One reason is that computers provided a solid visual aid to understanding what goes on inside the human mind. Previously, all was theory and speculation and hypotheses. After the computer, there were concrete processes that could be compared to the working of the human mind.
The computer program, a clearly reliable measure, could serve to represent what was going on "internally" in the human brain.(Richard H. Hall, Missouri State University)