Explanations of Forgetting

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Forgetting in the STM

decay theory- physical breakdown of an engram (memory trace), it gradually fades if there is no rehearsal (explains why forgetfulness increases with time) Peterson and Peterson (1959)- if participants were prevented for rehearsing a word list their recall would drop from 80% after 3 seconds to 20% after 18 seconds, the engram couldn't grow stronger and therefore broke down.

displacement theory- new information in the STM overwrites and replaces older memories (because of the limited capacity, Miller), when your memory is full old info will be pushed out Peterson and Peterson (1959) can also be used here because the world list could have been pushed out due to new information such as counting backwards (also Watkins et al and humming)

the idea that displacement and decay work together in the STM found by Shallice (1967) but displacement is the more dominant of the two

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Evaluation of Displacement or Decay in STM

Waugh and Norman (1965)- gave participants a list of numbers e.g. 31, 56, 85, 41, 22, 75, 63, 95, 51 then gave the probe e.g. 56, participats had to say what number followed the probe- they found that if the probe was early in the list recall was poor (less than 20 %) but recall was good if the probe was later in the list (over 80%), proving displacement 

HOWEVER... in later experiments this theory also proved decay- if the numbers were given in slower intervals e.g. one per second, recall wasn't as good because the numbers had more time to decay, but if the numbers were given at a faster pace e.g. four per second recall was a lot better. If displacement was the only factor there shouldn't have been a difference between the two recalls.

Evaluation of Peterson and Peterson- can be interpreted as both displacement and decay (same for Watkins)

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Forgetting in the LTM

MSM says that theLTM has an unlimited capacity and duration but we know that this is not true 

decay?- we forget things because the physical memory has been worn down over time. Lashley (1931) wanted to prove that memory has a physical basis and that forgetting is the result of the decay of a memory trace- used rats, taught them a maze and then removed parts of their brain to induce forgetting- did find a relationship between forgetting and the amout of brain removed

interference?- proactive- previous learning interfers with new learning and retroactive where new learning interfers with previous learning (e.g. rearranging things in a room and keep going back to their old place) Underwood and Postman (1960) used word lists A, B amd C- asked participants to learn word pairs from lists AB and then word pairs AC- found that recall was poorer from both lists when compared with a CG which proves proactive and retroactive interference 

cue-dependent forgetting?- not due to the loss of memory but the inability to access that memory e.g. if you were to be asked Freud's first name you might not recall but if someone said it began with an 'S' you then might be able to get to Sigmund' Abernethy (1940) found that students that sat a test in the same room they are taught in with the same teacher did better than others in different surroundings

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Evaluation of Decay, Interference and Cue-dependen

decay-? Jenkins and Dallenbach (1924) asked participants to recall a list of nonsense syllables and found that those who had 8 hours of sleep recalled more than those who were awake for 8 hours- disproving decay because if it was solely decay there wouldn't be a differecne in recall | this studly lacks internal reliability (consistency). 
Overall decay theory lacks support- doesn't explain how we can remember things from years ago e.g. flashbulb memories seem to be immune to decay 

interference-? Tulving and Psotka (1971) gave participants and categorised set of word lists e.g. furniture and animals- found that recall was highest in participants that didn't have to remember as many categories- supporting interference. HOWEVER... when given the name of the category recall drastically improved- supporting cue-dependency 

cue-dependent-? Goodwin et al (1969) people who forgot things when drunk remembered those things when drunk again- Miles and Hardman (1998) found similar results with exercise

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Repression- traumatic memories are repressed into the unconscious (Freud)

Mood-dependent memory- state dependent learning, depressed people will be able to remember memories encoded with a depressive state previously

Depression- shrinking in the hippocampus due to a rise in cortisol also low motivation and attention 

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