Memory is not a unitary system." Discuss the types of evidence that have been used to buttress this

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Memory is not a unitary system." Discuss the types of evidence that have been used to buttress this

What is a memory? Is it a concrete and tangible atom, which, once stored, can be retrieved by a methodical search or can it get lost in the murky recesses of our minds? Are our memories stored in separate areas or as part of one whole? In everyday conversation we regularly refer to memory in ways which suggest it to contain selective processes - 'I have a terrible memory for names', or 'I never forget a face' but is it really the case that our memory has specialised systems for the recall of certain information, or is it that memory is in fact a single system? Any discussion of the way in which we store information that can be accessed at a later date must address the issues raised here.

To look first at an overview of the architecture of our memories, we are probably all familiar with the idea of a short term and a long term memory. These two oft-used terms, along with the sensory memory, combine to make up the modal model. Several theorists such as Waugh & Newman (1965) have proposed a model in which we have these three separate systems, arranged in a hierarchy. Sensory stores feed into a phonetically coded short term memory via selective attention, and information then moves to a semantically coded long term memory. We will now look at each of these modules in turn and examine the ideas and evidence underlying each.

The sensory memory is proposed to be the interface with the outside world. Information is received from each of our senses (a separate, modality specific store is suggested for each sense) and held in a buffer which very quickly decays and is updated. There is good evidence for the existence of the brief storage of a verbatim copy of sensory input in several sensory modalities. The two most studied are in the visual and auditory modalities, dubbed by Neisser 'iconic' and 'echoic' memory respectively. Sperling (1960) provided some of the most striking evidence to date when testing recall of a briefly shown (50 msec) 3*4 grid of letters. The results were that typically, 4 letters were recalled. However, if given an auditory cue to focus on one row, 3 of the 4 letters in that row were recalled, suggesting that the amount of information available a fraction of a second after the stimulus had been shown was a great deal more than was available a second or so later. Indeed, further similar experiments have suggested that the iconic store decays within about 0.5 sec. Treisman (1964) and Darwin, Turvey and Crowder (1972) have investigated echoic memory using similar experiments and have found a similar decay effect, though in the auditory modality this appears to be of the order of around two seconds.

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Such experiments as outlined above seem to provide good evidence for the existence of a sensory store which is quite seperate from short term and long term memories and suggests that the human memory is modular at least in this respect. The existence of a sensory store also has great intuitive appeal when we consider the possible uses of such a system. Sensory memory appears to be preattentive and this seems a useful facility which could be held briefly to provide a steady input for later, conscious processing. Using this line of reasoning it could then be argued that sensory ...

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