Evaluation

• Clinical evidence


  One strength is evidence from the case studies of Henry Molaison and Clive Wearing:

  • Episodic memory was severely impaired due to brain damage
  • Their semantic and procedural memories were relatively unaffected
  • HM couldn't recall stroking a dog half an hour ago but did not need to have the concept of 'dog' explained to him
  • Clive still knew how to play the piano and sing
  • This supports Tulving's view that there are different memory stores in LTM - one can be damaged but others can still work
• Counterpoint to clinical evidence

  Clinical studies are not perfect. A major limitation is that they lack control variables. The brain injuries experienced were usually unexpected. Researchers have no control over what happened before the injury and have no knowledge of the individual's memory. Without this it is hard to measure change. This therefore limits what clinical studies can tell us about different types of LTM.
• Conflicting neuroimaging evidence


  One limitation is that there are conflicting research findings linking types of LTM to areas of the brain:

  • E.g. Randy Buckner and Steven Petersen reviewed evidence regarding the location of semantic and episodic memory.
  • Semantic memory is in the left side of the prefrontal cortex and episodic memory on the right
  • However, other research links the left prefrontal cortex with encoding of episodic memories and the right with episodic retrieval (Tulving et al. 1994)
  • This challenges any neuropsychological evidence
• Real-world evidence


  A strength is that understanding types of LTM allows psychologists to help people with memory problems:

  • E.g. as people age they experience memory loss. Research has shown that it seems to be specific to episodic memory - it becomes harder to recall past events
  • Sylvie Belleville devised an intervention to improve episodic memory of old people. The trained participants performed better on a test of episodic memory after training than a control group
  • This shows that distinguishing between types of LTM enables specific treatments to be developed