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HM Case Study
Transcript of HM Case Study
DoD: 02/12/2008 (age 82)
Henry Molaison (HM) had epilepsy. To fix his serve epilepsy he had surgery, cutting the over fired neurons in his corpus callosum. Something went wrong and he developed amnesia.
Who is HM
HM Case Study
Who Were the Researchers?
A case study is a collection of research methods including experiments, observations, interviews, MRIs Etc. It is an in-depth, intensive and sharply focused as it usually focuses on one individual, one family, one group or one institution. All case studies have a limited time scale as either the researcher is no longer able to continue their research or the person being studied is unable to continue or dies.
What is a Case Study?
Evaluation of HM
Use of HM Case Study in Research
Deception and Debriefing
Right of Withdrawal
William Scoville was a neurosurgeon in Hartford Connecticut. He was the surgeon of HM, conducting a bilateral medial temporal lobe resection to control HM's epileptic seizures. His seizures ceased but he no longer was able to form new memories.
Suzanne Corkin was the psychologist who studied HM's amnesia and drew conclusions about memory function and localisation of function.
She, and other psychologists first conducted MRIs on HM when he was 66 (1995). Previous imaging on HM's brain by Corkin (1984), did not show the extent of HM's temporal lobe lesion.
Scoville found that both the anterior Hippocampus and the hippocampus gyrus were both damaged in the surgery.
He concluded that they both played a part in forming new memories. It was not known whether or not the amygdala played a role in this mechanism.
Along side Scoville in 1957, Milner studied the damage to HM's brain. He had anterograde amnesia (not able to form new memories) and partial retrograde amnesia (he could access most of his but not all) She also discovered that HM still had procedural memories..
HM was unable to know he was being studied, therefore the researchers did not debrief him on what he was undergoing. This unlikely made a difference as he had would have forgotten what would have been debriefed.
HM was unable to withdraw from any of the studies that were conducted on him. If he did withdraw he would forget that he was being studied and could withdraw. If HM was uncomfortable with any of the situations he was in he would forget and then be unable to withdraw himself from the situation.
Informed consent is one of the major issues with HM's case study. HM, due to his anterograde amnesia, HM was unaware he was being studied, and therefore was unable to give consent. Even if he did give consent, it would be invalid due to his amnesia.
HM's full identity was mainly kept confidential, hese the use of his initials and not his name. His identity was eventually revealed and he is identifiable in footage from his studies.
The findings from the Studies in the HM Case Study have been used in other psychological research. The HM Case Study can be used when looking at cognitive and biological psychology. HM is a supporting study when looking at models of memory, specifically Multi-Store memory. HM demonstrates through his anterograde amnesia the loops between sensory, short term and long term memory and what happens when they are damaged. HM is also a supporting study (along side studies like Broca's 'Tan' (1981) in localization of function. HM demonstrated that the hippocampus plays a role in forming and retaining new memories
HM is a holistic study, many different types of research methods had been used to study HM.
The research is highly detailed and well documented.
The study is high in ecological validity as the study was not carried out with strict variables and was a real life example.
The case study was the only way to gain this information. Damaging a human on purpose so that these circumstances occur highly unethical. What happen to HM was an accident so using him was less unethical than recreating the situation.
The study focused on person and therefore only one specific situation was focused on.
The case study was a longitudinal study as it was carried out for a long time (from HM's surgery until he died).
Even after HM died his brain was studied post-mortem.
There is a lack of generalisability with case studies but HM has been generalized for certain situations.
Case studies are unreplicable, especially HM due to it being highly unethical to harm a human being in that manner for research.
There is the issue of researcher bias. This is limited by investigator triangulation.
Case studies are time consuming and costly
There are privacy issues with the participant. HM's identity was hidden to an extent.
There are four types of triangulation, three of which were used predominately in HM's Case study:
Methodological Triangulation: The use of different research methods, for HM there was the study of his surgery, MRIs, interviews, and the autopsy of his his brain when he died.
Investigator research: there were three main reserchers for HM, Scoville, Milner and Corkin. They each brought there own approach to the HM case study.
Theory Triangulation: HM can be looked at through two different theories in psychology: the cognitive (Models or memory) and biological (localization of function)
Theoretical: HM has been generalized to general ideas and concepts that have had further research. For example Multi-store memory.
Representational: Whilst HM is a case study and most findings from a case study cannot be a full representation of populations outside the person of study, findings from HM have been supported by other studies, for example Atkinson and Shiffrin (1968) for multi-store memory and Broca's 'Tan' (1981).
Inferential: HM's situation is very unique. It cannot be fully known if the findings can be applied to any context other than hippocampal damage in an epileptic patient. Although other studies into Localization of function and Multi-store memory suggest that it can be generalized to other settings and contexts.