STUDIES - Milner (1966) or HM

Question 1

Introduction

Answer 1

• Longitudinal case study

HENRY MOLAISON (HM):

• Hit by a cyclist when child and had serious head injury
• After injury, developed epilepsy
• When older, epilepsy was very severe and couldn’t maintain normal life as he didn’t respond to medication
• Neurosurgeon performed experimental surgery where he removed his hippocampus

Question 2

Aim

Answer 2

• Better understand the effects that the surgery had on patient HM

Question 3

Procedure

Answer 3

Method:

• Case study
• Used triangulation: Direct observation, interviews, MRIs…

Variables:

• No variables as it was not an experiment

Question 4

Results

Answer 4

• IQ and personality intact
• Significant anterograde amnesia: Could not form new explicit memories like semantic or episodic
• No retrograde amnesia: Had access to memories prior to surgery (LTM), but it got worse as years passed
• Unable to transfer information from STM to LTM
• Had working memory: He was able to carry out a normal conversation
• Could create procedural memory: Showed progress in reverse mirror drawing

Question 5

Findings

Answer 5

• Hippocampus plays a critical role in transferring information from STM to LTM
• STM is not stored in hippocampus: Could retain information for a while if rehearsed
• LTM is not stored in hippocampus: Could remember events prior to surgery
• Different memory types (procedural, semantic, episodic…) are found in different brain areas: Lost semantic but not procedural for example
• Biological evidence that STM and LTM are located in different areas of the brain

Question 6

Evaluation - Strengths

Answer 6

• Longitudinal (<50 yrs): Allowed
  1) Change to be observed over time
  2) Usage of different methods (triangulation)
  3) Formation of rich explanations
• High ecological validity: No variables manipulated as HM. was observed in his natural environment
• High ethical standards: Informed consent, no deception, withdrawal from participation

Question 7

Evaluation - Limitations

Answer 7

• Low replicability: Hard to falsify due to its focus on one specific patient
• Sample bias: Patient was a male of a certain age, doesn’t allow generalisability to different genders, cultures, or ages
• Potential researcher bias: Due to longitudinal nature, could have expectations…
• Retrospective: Little data on HM’s cognitive abilities prior to accident so hard to see what was caused by surgery
  — EXAMPLE: Unaware if medication had caused damage to brain (symptoms from medication or surgery?)
• Ethical issues: Confidentiality and anonymity was not preserved as we know the name of the patient