Psychologists such as Marigold Linton (1982) used a personal diary to record events in her own life in a pioneering study of autobiographical memory (found in Brace and Roth, 2007, p139). The primary strength of a diary study methodology is that it allows for the collection of data from real people in real situations allowing for high ecological validity. Investigators are able to collect a large amount of very specific data about events or psychological states of interest over time, from and insider viewpoint. Linton not only recorded the events but she also allocated specific meanings to the events, such as salience, importance and the emotionality of the event. This was done in an attempt to see if the type and depth of meaningfulness of the event, to the individual experiencing the event, would aid deeper coding of the event and thus better storage and clearer recall.
Linton found that only 30 per cent of events were forgotten all together at the end of the study. She associated this with repetition of similar events for example, knowing that you went to work but not knowing exactly what work you did on that particular day. Linton found no relationship between the emotionality and importance rating given initially and that given upon recall. This diary study in particular then, took six years to conduct but was unable to account for the significance of meaningfulness assigned from the insider viewpoint. However, Linton concluded that events could be recalled by a temporally ordered search of events she reported as being ordered chronologically. She suggested events were organised into categories and themes such as job and location at time of event. However, it can be argued that the mere act of writing events down could aid deeper encoding of the event and therefore better ability to store and recall the event.
Whilst the diary study used in this memory research failed to bring anything new or unique to the table with regards to introspection, it did however, compliment Conway’s (1996, found in Brace and Roth, 2007, p138) theories on autobiographical memories being linked to spatiotemporal knowledge. This also lends weight to the theory of sub-systems. Both methods used lead to theories which point to memories being organised in hierarchy with interlocking time periods and themes. There is no evidence that using the introspective viewpoint of diary studies contradicts the validity of the laboratory method.
Also supporting the idea of memory sub-systems are the neuropsychological case studies used by psychologists such as Vargha-Khadem (1997, in Brace and Roth, 2007, p148) and Warrington (1975, in Brace and Roth, 2007, p148). Neuropsychological case studies provide us with insights into patterns of memory deficits occurring when the brain has been damaged in some way. Memory deficits resulting from accidental damage suggests that different parts of the brain play different roles in memory. This is known as localised functioning and is also complimentary of theories concluded in the neuroscience approach. Evidence is based on case studies of neurologically ill or brain damaged individuals who show deficits in brain areas and from patients who exhibit double dissociations. The aim is to understand how the structure and function of the brain relates to specific psychological processes such as memory.
Case studies with neuropsychological impairment not only focus on behavioural data in memory tasks but also combines this together with information from brain lesions to draw inferences around areas of the brain involved in memory function. To do this it uses invasive techniques such PET and FMRI scans to study brain activity whilst cognitive memory tasks are being carried out. Using these techniques, studies such as that done by Vargha-Khadem (1997) found that children were able to retain factual information stored in LTM when the hippocampus area of the brain was damaged but the temporal cortex was still intact. Warrington’s (1975) and other recent studies lent support to this showing that damage to the temporal cortex, but not the hippocampus, allowed autobiographical memories such as routes and appointments from recent and past, to be recalled. These studies then relate the hippocampus to episodic memories and semantic memories to the temporal cortex clearly showing at least two different systems in use within memory tasks. These findings lend weight to Tulving’s (1972, in Brace and Roth, 2007, p149) theory that LTM can be divided into sub-systems of episodic and semantic memories.
Carters neuropsychological model showing the categorisation of semantic information by individuals suggests that individual experiences of sensory information and perceptual experiences are registered as masses of activity in cortical areas of the brain. He suggests that these are then fed to the hippocampus which replays them to the temporal cortex until they become established semantic memories. He is suggesting then that it is probable that these parts of the brain interact with one and other. Vargha-Khadem disagrees with this concept as in her study, when the hippocampus was damaged at birth, children were still able to acquire enough semantic memory to be in main stream school, implying that memories were being held without the hippocampus playing a part. However, it could be said that the two contrasting views could both be correct as compensatory mechanisms could be at work. The sheer complexity of the brain makes it hard to infer generalisations using individual cases. Assuming that different systems work together, damage to one part of the system may have knock on effects to other parts of the systems.
This method then brings new insight into the workings of memory systems and provides valuable and somewhat unique contributions for the construction of models of memory. It helps us to understand how memory usually operates and which parts of the brain are associated with memory processes. It also goes further to suggest that the sub-systems identified could work together promoting less fixity as previously suggested. However, neuropsychological case studies focus on brain damaged participants can damage the validity of the theories provided. Brain damage very rarely effects a single area of tissue and so is usually much more complex. Lesions on one part of the brain often invade adjacent structures which relate to other functions making it hard to pinpoint directly related behaviour. Although, by understanding what a person can no longer do, and correlating this with a knowledge of exactly which parts of the nervous system are damaged, it is possible to infer previously undiscovered functional relationships.
In summary, different methods rely on different kinds of data which in turn provide explanations and contributions to memory research at different levels of analysis. There is no evidence of any contradictory findings between the methodological approaches discussed. As discussed, each approach has its limitations but when combined together can produce a somewhat coherent overall picture of memory processes.
To conclude, diary studies contributed little in the way of understanding memory processes that wasn’t previously discovered. The findings of Linton’s study complimented the findings of the experimental methods. In doing so, the method introduced and highlighted the need for studying the subject from an introspective viewpoint, thus contributing a level of ecological validity to the overall findings of memory processes that were previously lacking. Neuropsychological memory research uses introspection combined with the study of memory processes at a biological level to contribute unique insight into areas of the brain associated with memory and how it works. The analysis resulting from this method compliments the findings of diary studies in relation to sub-systems. It is also a co-existing method in that it also contributes new ideas, such as suggesting the possibility that systems are not used in fixed sequences, but instead negotiate and interact with each other. It also allows us to see which parts of the brain are used for memory tasks.
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References
Brace, N. and Roth, I. (2007). Memory: Structures, processes and skills. In D.Miell, A. Pheonix, & K. Thomas (Eds.), Mapping Psychology (2nd ed., pp. 111-163). Milton Keynes: The Open University