Memory Evaluations Flashcards
MSM: Not unitary
One limitation of the MSM is evidence of multiple short and long-term stores. For example, KF suffered brain damage which resulted in difficulty dealing with verbal information in STM but a normal ability to process visual information. This suggests there must be at least two STM stores. In addition to this, several researchers have demonstrated that there are multiple LTM stores. Tulving suggests there are three separate LTM stores: procedural, semantic and episodic. This evidence suggests that the MSM may provide an oversimplified explanation of these memory stores.
MSM: Case Study Evidence
Psychologists have also shown that different areas of the brain are involved in STM and LTM from their study of individuals with brain damage. For example, HM had an operation to remove the hippocampus from both sides of his brain to reduce the severe epilepsy he had suffered.
Although HM’s personality and intellect remained intact, he could not form new LTMs. However, he could remember things from before the surgery. This provides support for the MSM’s notion of separate stores as HM was unable to transfer information from his STM to his LTM, but he was able to retrieve information from before his surgery (i.e. from LTM).
MSM: Research Support
One strength of the MSM is support from studies showing that STM and LTM are different. For example, Baddeley found that acoustically similar words were harder to recall immediately whereas semantically similar words were harder to recall after a 20 minute delay; thus indicating that STM and LTM are separate stores as each uses a different type of coding. Further support comes from research into the serial position effect (Glanzer and Cunitz) and studies using brain scanning techniques (e.g. Beardsley found that the prefrontal cortex is active during STM but not LTM tasks).
These studies clearly show that STM and LTM are separate and independent memory stores, as claimed by the MSM
LTM stores: Neurological Evidence
There is evidence from brain scan studies that different types of memory are stored in different parts of the brain. Tulving et al asked their participants to perform various tasks whilst scanning their brain with a PET scanner. They found that semantic memories involved the left prefrontal cortex whilst episodic memories involved the right prefrontal cortex.
This supports Tulving’s theory as it shows there is a physical reality to the different LTM stores. These findings have been confirmed in later research, further supporting the validity of the finding.
LTM Stores: Clinical Evidence
One strength of Tulving’s explanation of multiple LTM stores is that there is supporting evidence from clinical studies of patients with amnesia.
HM displayed normal functioning in his semantic memory (e.g. he understood the concept of a dog), but impaired functioning in his episodic memory (could not recall having recently stroked a dog). Clive Wearing was a professional musician and played the piano without difficulty, however he could not remember having learnt to play, suggesting an impaired episodic memory but functioning procedural memory. Both of these cases support the idea of a clear separation of different types of LTM, as although the episodic store was impaired in both cases the other stores were unaffected.
LTM Stores: Problems with clinical evidence
One limitation of using clinical evidence to support Tulving’s theory is that it is difficult to reach a firm conclusion. A major problem is that they lack control of variables. The brain injuries experienced by participants are usually unexpected. The researcher has no way of controlling what happened to the patient before or during the injury. The researcher also has no knowledge of the individual’s memory before the damage. Without this, it is difficult to judge exactly how much worse it is afterwards.
This lack of control limits what clinical studies can tell us about different types of LTM as we are not able to establish a causal relationship between a particular brain region and a type of LTM.
WMM: Clinical Evidence
Support for the WMM comes from the case study of KF, who was injured in a motorcycle accident. Following his accident, KF had poor STM ability for auditory information but could process visual information normally. For instance his immediate recall of letters was better when he read them (visual) than when they were read to him (acoustic). This demonstrates that KF’s phonological loop was damaged but his visuo-spatial sketchpad was intact. The research strongly supports the WMM and the existence of two separate slave systems, therefore providing support for the idea of a multi‐component STM system.
WMM: Research Support: Dual-task Performance
Further support for the WMM comes from dual‐task studies by Baddeley et al. When participants carried out a visual and a verbal task at the same time, their performance on each was similar to when they carried out the two tasks separately. But when both tasks were visual (or both were verbal), performance on both declined substantially. This is because both visual tasks compete for the same slave system (VSS), which has a limited capacity, whereas there is no competition when performing a verbal and a visual task together. Dual‐task studies provide evidence for the existence of multiple components within our STM and support the idea of a separate phonological loop and visuo‐spatial sketchpad.
WMM: Problems with the Central Executive
A limitation of the The WMM is that critics have suggested the concept of the central executive is too vague and doesn’t really explain anything.
Other psychologists have suggested that the notion of a single CE is wrong, and there are probably several components. This criticism is supported by case studies such as EVR, who had a cerebral tumour removed. He performed well on tests requiring reasoning, which suggested that his CE was intact. However, he had poor decision-making skills (e.g. where to eat), which suggests that there are several components and not all of his CE was wholly intact. Therefore, the account offered by the WMM is unsatisfactory because it is probably more complex than Baddeley and Hitch proposed and therefore challenges the integrity of the WMM.
Interference: Validity Issues
A limitation of interference as an explanation of forgetting is that as most supporting research (e.g. McGeoch and McDonald) is lab-based the findings may not be applicable to real-life. Researchers are able to control confounding variables so that studies show a clear link between interference and forgetting. One example of how this occurs is in the time periods between learning lists of words and recalling them. In lab studies, these time periods may be very brief (e.g. 20 minutes) and so therefore not reflect a real-life experience. The combination of artificial materials and unrealistic procedures pose a problem with this theory as it may not be a valid explanation for real-life forgetting.
Interference: Limited Explanation
One weakness is that interference may only offer a limited explanation of forgetting in everyday situations.
This is because the conditions necessary for interference to occur are relatively rare. This is very unlike lab studies, where the high degree of control means a researcher can create ideal conditions for interference. For instance, two memories have to be fairly similar in order to interfere with each other. This may happen occasionally in everyday life, but not often. This suggests that most forgetting may be better explained by other theories, such as retrieval failure due to a lack of cues, and therefore interference as an explanation of forgetting may have low external validity.
Interference: Real-World
One strength is that there is evidence of interference effects in more everyday situations. Baddeley and Hitch asked rugby players to recall the names of the teams they had played against during a rugby season. The players all played for the same time interval (over one season) but the number of intervening games varied because some players missed matches due to injury. Players who played the most games (most interference) had the poorest recall. They concluded that this was the result of retroactive interference, as the learning of new information (new team names) interfered with the memory of old information (earlier team names). This is a strength because it shows that interference can operate in at least some real-world situations, increasing the validity of the theory.
Retrieval Failure: Research Support
There is an impressive range of research support for retrieval failure as an explanation for forgetting. In addition to Carter and Cassaday’s study, other researchers have found evidence of state‐dependent forgetting using a range of different substances to create an alternative state of consciousness. For example, Darley et al researched the impact of marijuana on an individual’s recollection. It was found that individuals who were under the influence of marijuana when they put money in a ‘safe place’ were less able to recall where this location was once they were no longer under the influence of the drug. This evidence adds weight to the argument that the emotional and physiological state that a person is in at the time of encoding is important at the time of retrieval.
Retrieval Failure: Questioning Context Effects
One weakness is that context effects are actually not very strong, especially in real life. Baddeley argued that different contexts have to be very different for an effect to be seen. For example, it would be hard to find an environment as different from land as underwater. In contrast, learning something in one room and recalling it in another is unlikely to result in much forgetting because these environments are generally not different enough. This is a limitation because it means that the real life applications of retrieval failure due to contextual cues may not explain much forgetting.
Retrieval Failure: Recall versus Recognition
A limitation of retrieval failure as an explanation of forgetting is that contexts may depend substantially on the type of memory being tested.
Godden and Baddeley replicated their underwater experiment but used a recognition test instead of recall. Participants had to say whether they recognised a word read to them from a list, instead of retrieving it themselves. When recognition was tested there was no context-dependent effect, performance was the same in all four conditions. This suggests that retrieval failure is a limited explanation for forgetting because it only applies when a person has to recall information rather than recognise it.
