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Abstract:
Previous work (Gratton et al., 1997; 1998; Fabiani et al.,
submitted) suggests that the memory traces of stimuli studied under
divided-field conditions maintain information about the encoding
side. This is revealed by brain activity lateralized according to
the encoding side elicited by centrally-presented test stimuli
correctly identified as "old." This activity distinguished true
from false memories (Fabiani et al., in press). These results
suggest that the lateralized activity observed at test represents a
reactivation of the "sensory signature" generated at study. In this
experiment, we tested whether the encoding-related lateralization
remains stable or diminishes over a large number of items with
feature overlap. We also tested whether an encoding-related
lateralization is present for both correctly and incorrectly
recognized studied words. For each of six study phases, 60 words
were randomized and presented to the left or right of fixation. A
recognition test followed in which the 60 study words were randomly
intermixed with 60 new words. All test words were presented
centrally while event-related potentials (ERPs) were recorded.
Results indicate that the encoding-related activity diminishes over
the course of the experiment. They also indicate that this activity
is present for both correctly and incorrectly-identified words,
suggesting that subjects are unable to use this information to
improve their performance.
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