Memory Representations in Visual Working Memory: Representational Quality and Memory Access

다국어 초록 (Multilingual Abstract)

Previously, Shin and colleagues (2006) reported sequential deflections of encoding-related lateralization (ERL) waveforms in event-related potentials (ERPs). One of these deflections, observed at posterior electrode sites (P7/P8), started about 400 ms poststimulus, and was dependent on both memory set-size and the degree of matching between memory-sets and test probes. These suggest that there is a level at which relations among items and degree of memory access are important in visual working memory. Based on these findings the present study investigated representational quality and degree of memory access. It was hypothesized that representational quality could be lowered by competition between stimuli (local suppression), and that degree of memory access be lowered when probes only partially match memory-set stimuli (partial matching). The relative distance (close or far) and similarity (homogeneous or heterogeneous) between memory-set stimuli were varied. ERPs were recorded while participants made old or new responses to single probes preceded by memory-sets (of size 2 or 4). ERL results obtained from 33 participants showed (a) that large ERL effects were found at the P7/P8 sites with a latency of 400-700 ms from probe onset, similar to Shin et al. (2006); (b) that significant ERL activity was observed only for the homogeneous memory-sets presented far apart; and (c) that the heterogeneous memory-sets presented nearby showed significantly smaller ERL activity than set-size 2 memory-sets (representing no-suppression and complete matching). These results support a hybrid of the local suppression and partial matching hypotheses, suggesting that representational quality and degree of memory access can jointly influence visual working memory processing.

참고문헌 (Reference)

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