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Abstract:
Abstract: We present new findings that contradict the claim
that "hippocampal amnesic" H.M. exhibits a "pure memory deficit"
that has left his visual cognition intact. H.M. and memory-normal
controls of similar age, intelligence, and education were compared
on two tasks: discovering hidden figures (as in Thurstone, 1944),
and detecting errors in visual scenes, e.g., an upside-down
flowerpot. Targets in the hidden figures task were either familiar
(e.g., a square), or novel (e.g., a square with a V-shaped
protrusion on its left side). Relative to controls, H.M. exhibited
a deficit in detecting novel but not familiar targets. In the error
detection task, H.M. detected fewer errors and circled more
non-errors than controls. H.M.'s deficits in these tasks were not
attributable to miscomprehension of instructions, motoric
difficulties, general slowness, or low IQ. The results contradict
the claim that H.M.'s deficits are solely attributable to storage
processes that are independent of visual perception and cognition.
Instead the results support the account of H.M.'s deficits in
distributed-memory theories, which view memory storage and
retrieval as essential for perceptual representations of novel
visual forms. Under these theories, H.M. is unimpaired in the use
of old connections for recognizing familiar forms, but damage to
H.M.'s binding systems for facilitating the formation of new
connections underlie his deficits on both memory and non-memory
tasks.
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