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Abstract:
People perform better with old than new stimuli, with
"priming" being greater if the same rather than a different item is
re-presented. This pattern results from reinstantiation of the same
perceptual elements or reactivation of the same neural operations,
or both. We isolated their individual contributions in two
event-related potential (ERP) experiments on Gestalt perceptual
grouping processes. Degree of similarity between study and implicit
memory test objects (drawn with line segments separated in space)
assessed the role of process versus feature transfer in memory.
Studied pictures were the same fragments as at test, different
fragments than at test, or were complete with continuous contours
or segmented but not spatially-separated contours. Early (200 ms)
ERP repetition effects are form-specific: P200 effects are absent
if studied pictures were complete (no grouping) but present if they
were fragmented (grouping) despite differing from test pictures in
line location, orientation, or size. Transfer of grouping
operations not perceptual features matters. Later repetition
effects appear in all conditions: repeating the global form reduced
the frontal N400 despite changes in how contours were drawn. This
ERP indexes a structural description system implicated in object
priming. In sum, we find that implicit memory involves multiple
distinct stages, with some stages mediated by transfer of
processes, and not just features.
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