A general ability, or faculty, that enables us to interpret the perceptual world to help organize responses to changes that take place in the world. See also implicit, explicit, long term, short term memory.

William James (1890) claimed: "Memory proper is the knowledge of a former state of mind after it has already once dropped from consciousness; or rather it is the knowledge of an event, or fact, of which meantime we have not been thinking, with the additional consciousness that we have thought or experienced it before" (p. 648). However, despite the reasonableness of this claim, memory does not seem to be essentially intentional, as James assumed. Indeed, animals at all levels of organization exhibit some sorts of behavior that we associate with having a memory.
Generally, memory is evident upon an accumulation of experience of the perceptual world. This is experience is only useful, of course, if we are able to retrieve and apply it at the appropriate times. So, memory can be broadly characterized in terms of a repository of experience from which we can retrieve information and to which we can deposit information.
In the psychological literature the most common distinction between types of memory is that between long term memory (LTM) and short term memory (STM). However, it now seems over-simplified to think of memory as divisible into two precisely characterizable mental entities. As well, psychologists have posited an implicit/explicit memory distinction on the basis of evidence that such memories are experimentally separable. Brain imaging studies have suggested that such memories are processed in different areas of the brain. Finally, episodic and semantic memories are often distinguished. Episodic memories are those which give a subject the sense of remembering the actual situation, or event (e.g. Do you remember learning who the first president was? i.e. the event). Semantic memories are those in which the subject retrieves only general knowledge information (e.g. Who is the first president?) (Tulving, 1972).
The dominant metaphor for memory retrieval is association. Words, concepts and even feelings are seen as part of a large web, or network, with adjacent areas being more semantically (or perhaps otherwise) related (Anderson, 1976). Similarly, a 'schema' (frame or script) approach to understanding the organization of memory assumes experientially related nodes on a tree-like (Minsky, 1975).
Chris Eliasmith