memory Flashcards
The multi-store modelTh
The multi-store model of memory was devised by Atkinson and Shiffrin - linear model which shows how information flows from our senses to long term memory. It consists of 3 stores; the sensory register, short term memory (STM) and long term memory (LTM).
Information is first coded in to our sensory register in the form it appears to the senses (visually, acoustically etc). This store has a very large capacity but a very short duration (half a second).
If we pay attention to this sensory information it will transfer to STM (this is what we are thinking about right now).
STM has a capacity of 7 plus or minus 2 and duration of less than 30 seconds. Information is coded acoustically. If we use maintenance rehearsal, we can keep information in STM. If we use prolonged rehearsal, it will transfer to LTM.
LTM has a potentially unlimited capacity and can last a lifetime if we retrieve the information regularly. Information is coded semantically (by its meaning) in this store
The Multi store model A03
Support for the MSM comes from Baddeley’s research. Baddeley found that it was more difficult to recall acoustically similar words using STM and semantically similar words when using LTM. This supports the MSM’s claims of separate stores for STM and LTM that have separate coding.
However, the case study of KF can offer a contradiction to the MSM. KF suffered damage to his short term memory but only to information presented verbally. Information that was presented visually was not affected. This shows that the MSM’s claims of one single store for STM is too simplistic and that there must be more than one store as suggested by the working memory model.
Tulving’s research into types of LTM also undermines the MSM. Tulving used brain scans while ps were carrying out episodic and semantic tasks. He found that episodic tasks were processed in the right pre frontal cortex whereas semantic tasks were processed in the left pre frontal cortex. This suggests that there are more than one type of LTM contradicting the claim of the MSM that LTM is on store.
A further weakness of the multi-store model is that it relies on rehearsal for information to be transferred, however, rehearsal does not always ensure encoding and some memories do not require rehearsal to transfer to LTM including emotional experiences (flashbulb memories). Clearly the MSM is not a complete model of memory.
Key study for coding STM and LTM: Baddeley A01
Gave Ps acoustically or semantically similar or dissimilar words. Immediate recall was worse with acoustically similar words (because STM is coded acoustically) and recall after 20 mins was worse for semantically similar words (because LTM is coded semantically).
Key study for coding STM and LTM: Baddeley A03
Baddeley conducted a well-controlled study as shown by elements such as the time allocated to recall the specific word lists. This means that the study should have had few extraneous variables leading to good internal validity.
However, this study can be criticised for having artificial stimuli. The lists of words had no personal meaning to ps so the findings may not have been applicable to real life memory.
Key study for capacity in STM: Jacobs
Jacobs carried out a study in 1887 which we still study today. Participants were presented with a string of letters or numbers. They had to repeat them back in order and the strings increased until they were unable to remember. Most participants remembered about 7 letters and 9 numbers. Jacobs concluded that capacity of short term memory is about 5-9 items.
Key study for capacity in STM: Jacobs A03
This study was conducted a very long time ago. Early research often was not very well controlled so there may have been extraneous variables such as distractions in the study.
However, the findings of this study have been replicated by Miller who commented that the capacity of STM was 7+/- 2 so this strengthens the conclusions from Jacobs study.
Key study for capacity of LTM: Linton
Linton (case study) kept a diary of events over 6 years. She tested herself on events and facts about flowers every month. 5500 facts after 6 years. She was 70% accurate after 6 years.
Key study for capacity of LTM: Linton A03
This study was a case study which means the data may only apply to Linton. This is because she may be unique and her memory may be better than others. Perhaps she was even motivated to study memory because hers was good?
A strength of this study is that it studied an extreme case that could not be done as an experiment. If you asked a group of participants to spend such a large chunk of their life memorising events from every day, they would surely drop out of the study. Therefore this study is very useful in raising questions for future research
Key study for duration in STM: Peterson and Peterson
24ps were involved in 8 trials. Each trial involved being shown a consonant syllable (trigram eg XKC) to remember and a 3 digit number to count back from (in 3s) to prevent rehearsal for 3, 6, 9, 12, 15 or 18 seconds. 80% of ps could recall the trigram after 3 seconds. Less than 10% could recall after 18s. They concluded the STM has a limited duration (18-30s).
Key study for duration in STM: Peterson and Peterson A03
This study can be criticised for having artificial stimuli. The nonsense trigrams do not represent real life memory activities so the study lacks ecological validity.
The researchers in this study claimed that the interference task prevented Ps from rehearsing which is why information decayed, hence measuring the duration of STM. However some have argued that the interference task actually displaced the information (pushed it out of STM). So they may not have actually been measuring what they claimed and therefore it may have lacked internal validity
Key study for duration of LTM: Bahrick
Americans aged 17-74 were tested for recognition/ recall of classmates at school from their yearbook. Those 48 years after graduation were still 70% accurate in recognising classmates.
Key study for duration of LTM: Bahrick A03
This study had high ecological validity because it was testing the real life memories of its participants from high school. This means that we can apply the findings to real life memory.
However, there may have been some uncontrolled variables in this study. For example if participants looked at their year book regularly or stayed in touch with the people in it, their memory would have been better. This means that it may lack internal validity.
The working memory model a01
The working memory model was devised by Baddeley and Hitch - memory as short term storage and active processing involving qualitatively different subdivisions. There are 4 main components to the working memory model. The first of those components is the central executive. It guides our attention and decides what sensory information should be attended to. It directs the information to the 3 slave systems.
The central executive has a limited capacity with sensory coding. The first slave system is the phonological loop, it processes auditory information and is divided into the phonological store (stores words) and the articulatory process (repeats sounds while they are needed – It’s capacity is 2 seconds worth).
The second slave system is visuo-spatial sketchpad, it processes images and their arrangement (eg mental maps). It has a capacity of 3/4 objects.
The third slave system is the episodic buffer, it is a temporary store that integrates visual and auditory information to make events and links WMM with LTM it has a limited capacity of 4 chunks.
The working memory model A03
There is clinical evidence to support the working memory model from the case study KF. After a motorbike accident KF had impaired short term memory for information presented verbally but not visually. This suggests that his phonological loop was damaged but his visuospatial sketch pad was intact, supporting the existence of these separate stores. However, case study evidence should be viewed with caution. KF is just one person in a very rare situation so we cannot replicate this research to verify if the findings are applicable to other people’s memory. For this reason case study evidence can be argued to be unscientific.
Further evidence for the working memory model comes from brain scan studies which are much more scientific as they are replicable and involve objective evidence. Braver conducted a study in which he gave participants tasks that involved the central executive and found greater activity in the left prefrontal cortex (this increased as the task got harder). This suggests that the central executive does exist and it can be found in the prefrontal cortex.
This evidence clearly shows that the working memory model is superior to the multistore model in its representation of short term memory. The multistore model is oversimplified in its unitary representation of short term memory and its overreliance on rehearsal whereas the working memory model gives a more dynamic view of working memory which can explain how we can multi-task (using separate stores) whereas the multistore model cannot.
However, many psychologists argue that the central executive lacks clarity. Baddeley himself said that it was the most important but least understood part of the model. We need more information on its role than just ‘attention’. Therefore the working memory model is not fully explained
Improving the accuracy of EWT: The cognitive interview (RRRC)
Fisher and Geiselman created the following techniques to improve the accuracy of EWT and called them collectively “The cognitive interview”. There are four main techniques.
- Report everything: witnesses are encouraged to include every single detail of the event. Even if it seems irrelevant. This improves accuracy because details that seem unimportant might trigger more important memories.
- Reinstate the context: The witness should return to the crime scene in their mine (what was the weather like, where were you going?). Remembering the context will reduce the chance of context-dependent forgetting (it will provide cues to trigger memories).
- Reverse the order: Events are recalled in a different chronological order. This prevents people using their expectations of how the event must have happened from affecting recall. It also prevents lying
- Change the perspective: Witnesses recall from other people’s perspectives. This should also prevent expectations from influencing memory and reduce the chance of lying.
The enhanced cognitive interview also includes appropriate eye contact, reducing anxiety, minimising distractions and using open-ended questions.
