Long Term Memory

Long Term Memory

1. Bahrick Et Al 'Year Book study' (1975)

   • Findings
     • For participants that had left school up to 34 years previously, accuracy of recall on the face and name recognition tasks was still an amazing 90%. Even for participants who had left school 48 years previously it was 80%.
   • Procedure
     • 374 participants aged between 17 and 74 were tested on their memory of school friends. A number of different tests were carried out including a free recall of all the names of classmates they could remember, recognition of classmates from a selection of 50 photographs, a name recognition test and a photo matching test.
   • Conclusion
     • Recall can be accurate over a very long period of time, leading to the term vLTM (very long term memory) to describe this phenomenon.
   • Evaluation
     • The procedure used is a field experiment so is much higher in ecological validity since this is far more similar to the purpose we generally use our memories for.
     • However, the study was poorly controlled. The researchers assumed that last contact with their classmates would have been when they left school.

2. Evidence for two memory stores (STM and LTM)

   • Multistore model of memory
     • Primacy and recency effect.
       • Murdock (1962
         • Gave 103 psychology students lists of words to free recall (in any order) in 90 seconds. Typically words at the start of the list and especially those at the end tended to be recalled most often.
           • This was explained by words at the start being rehearsed from STM into LTM creating a stronger trace and those at the end still being present in STM when recall begins.

3. Amnesiac case studies

   • Most people with memory problems have either impairment of their STM or LTM, not usually both. This suggests that they are different systems.
   • HM (or Henry M)
     • The classic case is that of H.M who at the age of 27 underwent surgery in an attempt to cure his epilepsy apparently triggered by a cycling accident when he was nine
     • A surgeon, William Scoville removed both his temporal lobes including a structure known as the hippocampus (Latin for sea horse) and an area known to be crucial to memory.
       • Following the procedure HM was unable to create new long term memories. However his STM remained intact with a normal capacity and duration, limited only by his inability to rehearse.
         • HM therefore could be taught new skills, which over time would improve with practice. However, he would have no recollection of ever having performed them before
   • KF
     • Suffered damage to his STM following a motorcycling accident still retained a near normal LTM
     • KF could still recall visual information using his STM but struggled with auditory and verbal information, making conversation difficult

4. What amnesiacs tell us about memory

   • We therefore have a situation were cases of amnesia can both support the idea of two memory stores whilst at the same time question the idea
   • Two memory stores
     • Amnesiacs tend to lose only one store (either STM or LTM) supporting the idea of two separate stores presumably located in different brain areas or structures
   • More than two stores
     • However, HM and Clive Wearing both provide us with evidence that LTM is more complex and seems to comprise at least two components (semantic and episodic LTM).
       • Similarly KF suggests that STM is also more complicated having separate stores for both auditory and visual information

5. The prefrontal cortex is active when STM is being used whereas the hippocampus in the temporal lobes is active for LTM.

Imagens e arquivos do mapa