Multi-store model of memory studies

Multi store model of memory:

Information we recieve from the environment goes into our sensory store (capacity: unlimited, duration: fraction of a second, encoding: the same as how it is recieved)

Then, if attended to, the information is stored in short term memory (capacity: about seven items, duration: about half a minute, encoding: accoustic for easy rehearsal)

Then, if rehearsed, the information goes into long term memory (capacity: unlimited, duration: half a minute to a lifetime, encoding: semantic)

The studies that follow are evidence to support this multi-store model...

Procedure: Participants were given a list of 15 words to remember. Some recalled the words and said them immediately to the investigator. Some recalled them after a 10 second delay, during which they counted backwards to prevent rehearsal.

Findings: Words near the start of the list "primary words" were well remembered (both with and without delay) suggesting they had been transfered to LTM. Words near the end "recency words" were badly effected by a delay when rehearsal was prevented, suggesting they were in STM. The loss of "recency words" suggests that the model is right as, because they couldn't be rehearsed, they were lost from STM.

Conclusion: STM is a seperate store from LTM, info. has to be rehearsed to transfer to LTM or it will dissapear from STM after a few seconds.

Criticisms: Strength - can control extraneous variables (lab experiment)     Limitation - possible for participants to manipulate results, especially if they can guess what the experiment is about : "participant rectivity".

Procedure: They showed participants a series of tri-grams (three letters in a row e.g KMJ) for one second, then they were asked to recall them after a delay. As soon as they had seen the tri-gram, participants were asked to count backwards in threes to stop rehearsal. Participants were stopped after a delay of 0 seconds, 8 seconds, 16 seconds, 24 seconds, 32 seconds and 40 seconds.

Findings: If rehearsal is prevented, recall of trigrams is very low after about 20 seconds, suggesting that half a minute is a realistic estimate for the duration of STM.

Conclusion: The duration of STM is about half a minute.

Criticisms: Strength - can control extraneous variables (lab experiment)  Limitation - possible for participants to manipulate results, especially if they can guess what the experiment is about : "participant rectivity".

Procedure: Participants had lists of 5 words to remember. They looked at each list for a few seconds, then were immediately asked to recall the words. How many they got right was recorded. Then they came back the next day to see what they remembered. There were two types of lists. In one type the words sounded similar. In the other type they were semantically similar.

Findings: When recalling words immediately, they got muddled with the semantically similar words, suggesting that STM is accoustically encoded. When recalling words the next day, they got muddled oin the similar sounding words, suggesting LTM is semantically encoded.

Conclusions: Accoustic encoding is important in STM whereas semantic encoding is important in LTM

Criticisms: Strength - can control extraneous variables (lab experiment)     Limitation - possible for participants to manipulate results, especially if they can guess what the experiment is about : "participant rectivity".

Procedure: He found people of a range of different ages, and showed them old school photos, asking them to identify their old classmates. He also tested them on their knowledge of school algebra and school Spanish.

Findings: He worked out that people lose about 1% of information per year if the material they are trying to remember had been well learned in the first place. Since a lot of material is still remembered (50% after 50 years) this suggests that memories can have a very long duration... perhaps a lifetime.

Conclusions: The duration of LTM can be as long as a lifetime.

Criticisms: Strength - can control extraneous variables (lab experiment)     Limitation - possible for participants to manipulate results, especially if they can guess what the experiment is about : "participant rectivity".                         Limitation - "individual differences" because participants might still be learning Spanish for example and will therefore have a better memory of it.

Procedure: Participants, who's ages ranged from eight years to adult, were shown sequences of numbers or letters at half second intervals for each item. Jacobs started with three items then graduately increased the number until the participant had only a 50% success rate at recalling them.

Findings: for letters and for words the number remembered was between about 5 and 9. The mean for numbers was greater than for letters. Children had a smaller capacity than teens and adults.

Conclusion: The capacity of STM is about seven items, plus or minus two, and it depends only lightly on the type of stimulus material used. Capacity in children is less than in adults, and increases gradually with age.

Criticisms: Strength - can control extraneous variables (lab experiment)     Limitation - possible for participants to manipulate results, especially if they can guess what the experiment is about : "participant rectivity".

A former musician called Clive Wearing caught a brain infection and damaged his hippocampus. He can remember things that were in LTM before his illness, but he can't form new information from STM into LTM. This means he hasn't learned anything new for many years.

This also supports the multi-store model as it helps to prove that STM and LTM are different stores, and also that the duration of STM isn't very long.