Although the belief that memory is composed of several distinct systems is not novel, it is only around the mid 20th century that experimental studies carried out on amnesic patients have started to confirm it (Squire, 2004). This essay will discuss the different types of memory systems that have been found, their distinctions and evidence supporting their existence derived from studies on amnesiacs.

Atkinson and Shiffrin’s (1968) multi-store model suggests that memory is a flow of information processed through three stores (Myers, 2010). The first system called sensory memory (SM) processes mainly visual and auditory information from our environment (Myers, 2010). It is made up of several components associated with each sense and …show more content…
They referred implicit memory as procedural memory involved in knowledge of skills which would explain why HM could still learn new motor skills (Groome, 2006). According to Tulving, Schacter and Stark (1982), declarative or explicit memory can be further separated into two conscious systems: episodic and semantic memory (Squire, 2004). Episodic memory contains autobiographical contents, is a record of a person’s personal history such as birth dates and deals with past experiences (Tulving 1972; 1993; 2002). In contrast, semantic memory is a storage system of facts, meanings of words and general knowledge of the world such as the capital of cities (Tulving, 1972).

Research on memory is arduous and the problems questioned are not easily solved (Tulving, 1985). At the beginning, the answer to the title question would be ‘three’ but when looking into further research based on studies of amnesiacs, the number increased to about approximately ‘seven’. However, being aware of the difficult nature of memory and the limitations of its study, the more reasonable and sensible answer would be ‘at least three and probably many more’ (Tulving, 1985).

References
Atkinson, R. C., & Shiffrin, R. M. (1968). Human memory: A proposed system and its control processes. In K. W. Spence & J. T. Spense (Eds.), The psychology of learning and