Memory models

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CAPACITY

1) Sensory Register - Sperling (1960) ppts were presented with a 3x4 letter grid for 1/20th second. When a high,medium or low pitched tone was produced to indicate which row was to be recalled ppts scored 3/4. Since ppts did not know which row they had to recall the information had to be available from somewhere. This has suggested that the capacity of the sensory register in unlimited

2) STM - Jacobs ' Serial digit span technique' between 5 and 9 items. Miller (1956) conducted a review of studies that had investigated the capacity of STM which supported Jacobs study, concluding that the capacity of STM was 7+-2 items.

3) LTM- Unlimited

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DURATION

1) Sensory register - 250 milliseconds

2) STM - Brown-Peterson technique. Participants were briefly shown consonant trigrams and were given an interferance task of counting backwards in 3's to prevent reherasal. After intervals of 3,6,9,12,15,18 seconds they were asked to recall the trigram. The interference task didnt affect the recall after 3 seconds but as time increased between presentation of trigram and recall, performance declined. After 18 seconds, the memory trace for the trigram has decayed. Peterson and Peterson condluded the duration is approx 18 -30 seconds

3) LTM - Bahrick et al (1975) showed 400 participants aged 17-74 years a set of photots and a list of names, some of which were old school friends, and were asked to identify their old school friends in the photos. Those that had left school 48 years previously recalled 80% of names and 70% of faces suggesting that memory for names and faces is long lasting.

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CODING

1) Sensory register -  Modality specific i.e there are seperate sensory stores for different sensory inputs

2) STM -  Baddeley (1966) found that when ppts were given a short term memory task there was acoustic confusion with words that sould alike. When given a long term memory task there was sematic confusion with words with a similar meaning.

Coding in STM in acoustic and in LTM semantic

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Components of the WMM

1. Central Executive - Supervisory component which has overall control over the other three slave systems. It plays the most imporant and complex role in working memory as it controls which information is and is not attended to. It also plays a major role in planning and combining information from the three slave systems. The central executive has limitied capacity and can only attend to a limited number of things at one time. 

2) Visuo-spatial sketchpad - Function is to hold a limited amount of information coded in a visual form for a short period of time. This sytem helps individuals to navigate and interact with their physical environment. Includes the visual cache, a passive temporary visual store which is linked to an active inner scribe that acts as a rehearsal mechanism.

3) Phonological loop- Function is to store a limited number of speech based sounds for a brief time. It is made up of a phonological store, known as the inner ear which stored acoustically coded items and an articulatory process, known as the inner voice which allows words to be kept in memory by sub vocal repition

4) Episodic buffer - Added in 2000, temporary store responsible for integrating the visual, spatial and verbal information from the other stores and has a limited capacity of about 4 chunks

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