PSCH 352, Summer 2005
Notes, 6/16

First: Finish LTM notes from 6/15 about losing information from memory

Where can forgetting happen?
1. encoding –
2. storage –
3. retrieval –

availability vs. accessibility

example of retrieval failure – tip-of-the-tongue (TOT) effects –

Extreme forgetting – amnesia
loss of memory or memory abilities caused by brain damage or disease

two types
1. retrograde amnesia – loss of memory for events that happened before damage
2. anterograde amnesia – loss of memory for events that happened after damage (ie, the inability to form new memories)

Retrograde and anterograde amnesia illustrate the idea of a double dissociation – two components of
the memory system in which when one is disturbed, the other is not.  For example, HM cannot form new
memories, but he can remember events from before his surgery.

KC – retrograde amnesia.  KC was in a motorcycle accident and received severe damage to his frontal lobes. 
He cannot remember anything that happened to him before the accident.  He also has some anterograde amnesia,
in that he does not have episodic memories for after the accident.  However, he can form new semantic memories,
and new procedural memories.  His semantic memory for prior to the accident is also intact.  For example, KC
remembers facts that he learned in school (semantic memory) and can learn new facts.  He also remembers old
procedural memories, like playing chess, and can learn form new procedural memories.  KC shows how episodic
and semantic memory are double dissociated.

HM – anterograde amnesia.  HM’s hippocampus (in both hemispheres) was surgically lesioned in 1953 as an
attempt to control his epileptic seizures.  The hippocampus is involved in the formation of new memories, and as
a result HM was unable to form any new memories, episodic, semantic, or procedural.  In short, he could not form
any new explicit memories.  However, HM did show implicit learning.  He was taught to do 2 tasks – mirror-tracing,
and the Tower of Hanoi.  Although HM had no explicit memory for how to do these tasks, he took less and less
trials over several days to learn them.  In this way, HM showed implicit learning for the tasks.  HM shows how
explicit and implicit memory are double dissociated.

How do we study implicit memory?

Discussion of HM and KC articles