Problem Search #4							Kevin Driscoll
									Seth Stocking

Discover Magazine January 1997

Brain: When Memories Lie

Last August a group of Harvard researchers captured the first glimpse of the brain
as it retrieves both true and false memories.  They read several lists of semantically
related words to 12 adult subjects.  After ten minutes subjects were shown words from
each of the lists and asked if they had been among the words the subjects had heard.  As
they were thinking a PET scan was monitoring their brain activity.  The subjects were
then shown another list, containing only words similar but not identical to the words on
the original lists.  This meant that any recognition of the words would constitute a false
memory. 

 
	As would be suspected the subjects were slightly better at recognizing words they
had actually heard.    Both tests, however, showed activation in the medial temporal lobe. 
In the first test when subjects were asked to recall words they had actually heard, an
additional region in the temporal lobe was stimulated  The region stimulated is thought to
process sounds, says Daniel Schacter, a cognitive neuroscientist at Harvard, and its
activity may reflect the auditory memory of how the words sounded when they were read
aloud.  While subjects were pondering whether they heard a "false" word before,
Schacter notes, their brains sometimes showed activity in the frontal cerebral cortex--the
decision-making center--as if they were frantically searching for sensory evidence.

What issues and principles in cognitive science does this bring up?

What is the nature of memory, for example? Exact storage? Reconstructed information? What do so called "false" memories say about the way the mind recodes input into mentalese?

What does this say about modularity? Is there a module that constitues control of searches (frontal area) -- as if the brain had a kind of search engine bundled with its operating system? Kossly and Koenig in Wet Mind say as much for searches in visual knowledge, where the frontal lobe is implicated in the matching of spatial properties.