The director of the Center for Cognitive Neuroscience at MIT has synthesized cognitive science and evolutionary biology to present the human mind as a system of mental modules designed to solve the problems faced by our evolutionary ancestors in their foraging way of life. He brings together two theories: the computational theory of mind, which says that the processing of information, including desires and beliefs, is the fundamental activity of the brain, and the theory of natural selection. He suggests that four traits of our ancestors may have been prerequisites to the evolution of powers of reasoning: good vision, group living, free hands, and hunting. He believes that human brains, having evolved by the laws of natural selection and genetics, now interact according to laws of cognitive and social psychology, human ecology, and history.


Intelligence is defined as the ability to use knowledge of how things work to attain goals in the face of obstacles. It is suggested that the mind uses mental representations in order to build generalizations and that the everyday ease of generalizing knowledge is one type of evidence that the mind uses several kinds of data representations. In building generalization the mind builds categories that are simultaneously fuzzy (predictive power comes from similarity) and crisp (predictive power comes from deduction) (Pinker, 1997).


The structure of the human memory system leads to imperfections in what people know and leads to the conclusion that people "don't completely know what they know". For instance when we know a subject in depth much of the knowledge has become automated and is not available to working memory making it difficult for individuals to explain what they know. Working memory is considered to be the centre of the conscious self because it is where conscious and explicit reasoning takes place (Wiig, 1993). There is a capacity limitation on working memory that will allow no more than seven to nine "chunks" (mental models) to be accessed at one time. A "chunk" can be complex or can be an abstract concept or phrase (Miller, 1956). Conscious working memory contains three specialized control functions: central executive - what we think about; visuo-spatial scratch pad - holds active chunks and associations; and the articulatory loop (phonological loop) - speaking, writing, non-verbal gestures.

Medium-term or "buffer memory" stores a large number of mental objects that are currently being worked with or have been worked with over the past couple of hours. Two features of buffer memory are of interest: mental objects are easily accessible by working memory, although they are also easily forgotten; each individual retains mental objects differently, a relevant fact when understanding how individuals obtain and use knowledge.

Long-term memory uses mental objects to store information and knowledge for long periods of time. Permanent links that in some way represent what is know are created.

Making Use of Memory

It is suggested that long term memory can be organized into four categories, each of which serve a different purpose: procedural, episodic, priming and semantic. Procedural memory is where we remember how to do things and is where we keep mental objects like: schemas, scripts, and routines. These mental objects are held in the form of sequential steps. It is usually difficult for someone to explain what is known in procedural memory yet the performance of the task can be triggered by a "cue. Episodic memory is the repository for personally experienced episodes or events, which are stored without further analysis or integration into what is known. Episodic memories are considered to be information about an event rather than knowledge because the event has yet to be internalized or analyzed (Tulving, 1972). Episodic memories are subjective and seem to be narrow in focus with only a particular aspect being remembered to the exclusion of everything else. Factual knowledge is stored in semantic memory and this is where meaning is attached to the knowledge. Semantic memory is used to recall mental objects which are expressed as abstract thoughts (cognition) rather than behavior. There seem to be two sub-categories within semantic memory: lexical memory - holds knowledge about language and contains semantic labels that are used to describe concepts, it contains knowledge of what is known; encyclopedic memory - holds the detailed knowledge itself and is said to store language-free concepts. Priming memory identifies and recognizes mental objects as "cues". When valid cues are recognized a larger associated chunk is triggered. Priming memory uses associative links to point to knowledge stored in semantic memory. Priming memory is the repository for context dependent cues and contributes to the performance and exercise of expertise in daily work and is of particular importance to "practical knowledge workers" (Wiig, 1993).

Concepts are formed from the totality of what is remembered and are used as associative or mental building blocks. It has been suggested that episodic and semantic memories together form conceptual memory. The explanation of behavior is thought to lie in procedural memory while cognition is thought to lie in episodic, semantic and priming memories.

A Paradox

In spite of complex cognitive processes, humans still have difficulty telling fact from fantasy. Once something has been imagined it seems to be integrated with other things as if it were fact. Opinions and judgments seem to be based on an individual's knowledge and how they interpret the world around them resulting in knowledge workers and experts often presenting an imperfect understanding as truth (Wiig, 1993).

Miller, G. (1956). The magical number seven, plus or minus two: Some limits on our capacity for processing information. Psychological Review, 63, 81-97.

Pinker, S. (1997). How the mind works. New York NY: W. W. Norton & Company, Inc.

Tulving, E. (1972). Organization of memory. New York NY: Academic Press.

Wiig, K. (1993). Knowledge management foundations: Thinking about thinking - How people and organizations create, represent, and use knowledge. Arlington TX: Schema Press.