Explanations of Forgetting

FORGETTING IN STM

• DECAY THEORY= Memory trace refers to the physical representation of info in the brain. It is suggested that this trace can simply disappear or decay if it isn't rehearsed. This is shown in Peterson and Peterson's experiment where no rehearsal was permitted and most of the info had disappeared from the STM in around 18 seconds.
• DISPLACEMENT THEORY= New info physically overwrites or 'pushes' old info out. this happens because the STM has reached its full capacity.

EVALUATION

• Peterson and Peterson's experiment appears to show that info decays within 18 seconds from the STM if verbal rehearsal is prevented. however, it's possible that the info didn't disappear but it was displaced by the numbers used to distract the p's attention
• Reitman tried to overcome this problem of displacement by giving p's a different task in the retention interval. She asked p's to listen for a tone. This meant their attention was diverted elsewhereand should have prevented rehearsal of data. in a 15 second interval, p's recall dropped by 24% which is evidence for decay but we can't be entirely certain that new info had not entered the STM.  

FORGETTING IN LTM

• DECAY THEORY= Individuals who suffer brain damage where parts of the brain no longer function correctly experience firgetting. In the this case, it is the loss of the memory trace that causes forgetting. Lashley conducted some famous experiments on rats he trained them to learn the route in a maze and then removed certain parts of their brain. he found that there was a link between the amount of brain removed and the amount forgotten. this shows that LTM forgetting may be related to physical decay
• INTERFERENCE THEORY= this is where memories interfere with other ones e.g. getting a knife…