HM Case Flashcards
What was the aim of the study?
To understand the effects the experimental surgery had on patient HM.
What method was used? Explain.
Method of triangulation was used: Psychometric testing (IQ) Observation of behaviour Interviews with HM and family Cognitive testing (memory recall tests, learning tasks (reverse mirror drawing)) MRI to determine damage to brain
What did they find out about HM’s episodic and semantic knowledge?
HM could not acquire new episodic knowledge (memory for events) or new semantic knowledge (general knowledge)
Suggesting that brain structures removed were important to transfer of information from short term to long term memory
What did they infer by the fact that HM could draw a spatial layout of his house?
He could perform a cognitive map, and therefore this type of memory is not encoded in the same way as semantic or episodic
What did they find about his working memory?
He had capacity for working memory, he could carry a normal conversation, which requires minimal retention of what has been seen and heard short term.
Could recall number 584 even 15 minutes after being asked by means of constant repetition. After task was over, could not recall
What was well maintained
Motor skill memories, or procedural memories. Could mow a lawn. Showed improvement on performance of new skills, like Reverse mirror drawing (required acquiring new hand-eye coordination)
Showed improvement on skill over time but couldn’t remember learning it
What did the MRI find?
Hippocampus had most damage, explains problem with transferring short-term memory to long term. This is area where neurotransmitter acetylcholine is believed to play an important role in learning and formation of memories
What were the conclusions?
Memory system highly specialised and complex
Hippocampus has critical role in connecting short-term and long-term memories (converting)
Short term memory not stored in hippocampus, because HM was able to retain information for a while if it was rehearsed, just couldn’t transfer it to long term. Medial temporal region not site of permanent storage, but plays role in organisation and permanent storage of memories elsewhere in brain. This is supported by the fact that HM is able to retain memories for events that happened long before surgery
Implicit memory contains several stores
Procedural memory, emotional memory, skills and habits
Each related to different brain areas
What are strengths of the stody
- longitudinal
- change could be observed over time
- used triangulation, meaning it got rich data, higher credibility
- Higher ecological validity
- Met ethical standards of consent, confidentiality and protection from harm
Limitations
Cannot be replicated, but other studies like Clive Wearing confirm findings
- Retrospective
- Do not have data on HM’s cognitive abilities before surgery
- Medication treating epilepsy could have caused damage
