Since the 1970s, cognitive psychologists have been proposing various models of human cognition. They all differ in detail, but there has also been convergence on some broad themes. This isn’t surprising, as they must all deal with a growing collection of experimental results.
These researchers don’t claim that the human mind is physically structured as the information-processing models suggest. They have presented a great deal of experimental evidence, however, that these models do describe the apparent behavior of the human mind. Most importantly, these models are becoming increasingly effective at predicting the behavior of the human mind under particular circumstances.
The first common idea is the notion of multiple control modes. Conscious controlled thought is one mode. Subconscious automatic thought is another mode. Both modes of thought occur simultaneously and independently.
Conscious thought, which is the focus of our attention, is relatively slow. It requires effort to sustain, and one thought activity follows another sequentially. When we use conscious thought, we set goals, select the means for achieving those goals, and monitor our progress. This type of thought can perform the type of inference associated with classical logic.
Subconscious thought, which doesn’t require our attention, seems to proceed more quickly. This type of thought processes familiar information quickly, in parallel, and without conscious effort. This type of thought matches activation conditions with sensory input or intentional input.
The second common idea is the concept of cognitive structures. Working memory is used by the activities of conscious thought. The knowledge base is used by the activities of subconscious thought.
Working memory has a very limited storage capacity, typically judged to be less than ten items. Items are stored in working memory according to the recency of their arrival. They depart from working memory as other items arrive and push them out. The capacity of working memory can be leveraged by hierarchical structure.
The knowledge base contains logical data structures. Some theorists assert that the knowledge base contains two types of information: declarative and procedural. Declarative knowledge seems to include propositions, lists, and images. People learn such information quite quickly.
The procedural part of the knowledge base contains interrelated data structures with a uniform format. Many theorists assert that the procedural data is structured as rules. The rules have a set of conditions (the if part) and actions (the then part). If the current state of processing matches the conditions in a rule, the actions are executed. Actions can activate other rules, which cause us actually to do some physical action, move information into working memory for conscious processing, and so forth. People learn procedural information more slowly.
Based on this model, many cognitive psychologists believe that human thought is mostly pattern matching the activation conditions of rules, rather than logical deduction. These rules are generated by past experience. The common situations that we encounter are recorded. When exceptions to these situations are encountered, they’re recorded in separate rules. Memory is biased toward generalization and regularization of common situations and emphasizing exceptional properties.