| |
Abstract:
We examined memory for visual stimuli by recording behavioral
and event related potential (ERP) responses to line drawings in an
incidental memory task (Exps. 1, 2 & 3) and in an intentional
(recognition) memory task (Exp. 4). In Exp. 1, responses to
immediately repeated non-target stimuli were faster (40 ms) than to
first presentations. Furthermore, repeated stimuli elicited less
negative ERP waveforms at frontal sites (250500ms) and less
positive ERP waveforms at parieto-occipital sites (after 400ms) as
compared to first presentations. In Exp. 2, three to five stimuli
intervened between first and second presentations. There was a
reduction in reaction time with stimulus repetition (10ms) and a
frontal ERP effect similar to Exp. 1. In Exp. 3, repetitions of
semantically identical but physically different stimuli elicited a
frontal effect similar to Exps. 1 & 2. The frontal ERP effect
observed in all experiments is most consistent with stimulus
familiarity. The parietal reduction in positivity to repeated
stimuli (Exp.1) may reflect availability of a stimulus specific
short-term memory representation (i.e., a token) that is written
over by intervening stimuli and is not activated by physically
different stimuli. This representation appears to be distinct from
that accessed by intentional retrieval because repeated stimuli
elicited more positive parietal ERP waveforms in Exp. 4.
|
