간격을 두고 반복(간격반복)되는 항목이 간격 없이 반복(집중반복)되는 항목보다 기억 수행이 우수한 간격효과 기저의 부호화 기전을 ERP 연구를 통해 밝히기 위해, 단어의 의도학습을 요구한 부호화단계에서 간격반복, 집중반복, 한번만 제시되는 비반복의 세 조건을 조작하고, 인출단계에서 재인-확신도 평정검사를 실시하였다. 재인-확신도 평정반응의 분석 결과, 확신-적중 반응에 있어 간격반복, 집중반복, 비반복 조건의 순으로 확신-적중율이 높았다. 부호화 도중 측정한 ERP의 시간창별 평균진폭을 분석한 결과, 집중반복 항목은 간격반복 항목과 비반복 항목에 비해 자극제시 후 초기(230-330ms)에는 평균진폭이 더 높았고 그 이후(330-540ms)에는 평균진폭이 더 낮았다. P300 정점의 진폭과 잠재기를 분석한 결과 집중반복 항목은 간격반복 항목과 비반복 항목에 비해 진폭이 더 낮았고 잠재기가 더 짧았다. 간격반복 항목은 자극 제시 후 230ms부터는 평균진폭, 전위 두피분포, P300 진폭과 잠재기에 있어 비반복 항목과 차이가 없었다. 이러한 결과는 간격효과가 부호화 도중 학습항목에 배당되는 주의량의 차이에 기인한다는 것을 보여주는데, 집중반복 항목이 새로운 항목이나 간격반복 항목에 비해 더 적은 양의 주의를 배당받기 때문에 결핍된 처리가 일어나서 간격반복 항목보다 기억 수행이 더 저조하다는 것을 시사한다.
Memory for repeated items improves when presentations are spaced during study (spacing effect). To examine the neural mechanisms underlying the spacing effect, event-related potentials (ERPs) were recorded during intentional study phase of a recognition memory paradigm. During study, words were presented once (no repetition) or repeated immediately (massed repetition) or repeated after 6 intervening items (spaced repetition). Participants were then asked to do old/new and confident/no confident judgments. Confident-hit recognition was better for repeated items with delay than immediately repeated items. Mean amplitudes at 230-330ms interval were more positive for massed repetition compared to spaced and no repetition conditions, but mean amplitudes at 330-540ms interval were more positive for spaced and no repetition compared to massed repetition condition. P300 peak amplitudes were more positive for spaced and no repetition compared to massed repetition condition and P300 latencies were shorter for massed repetition compared to spaced and no repetition conditions. In terms of mean amplitudes of time intervals after 230ms, P300 peak amplitudes/latencies, and scalp distributions of potentials, no difference was found between spaced vs. no repetition conditions. These results show that smaller amount of attention is allocated to immediately repeated items than to repeated items with delay. Spacing effect could be explained by deficient processing of immediately repeated items.
Memory for repeated items improves when presentations are spaced during study (spacing effect). To examine the neural mechanisms underlying the spacing effect, event-related potentials (ERPs) were recorded during intentional study phase of a recognition memory paradigm. During study, words were presented once (no repetition) or repeated immediately (massed repetition) or repeated after 6 intervening items (spaced repetition). Participants were then asked to do old/new and confident/no confident judgments. Confident-hit recognition was better for repeated items with delay than immediately repeated items. Mean amplitudes at 230-330ms interval were more positive for massed repetition compared to spaced and no repetition conditions, but mean amplitudes at 330-540ms interval were more positive for spaced and no repetition compared to massed repetition condition. P300 peak amplitudes were more positive for spaced and no repetition compared to massed repetition condition and P300 latencies were shorter for massed repetition compared to spaced and no repetition conditions. In terms of mean amplitudes of time intervals after 230ms, P300 peak amplitudes/latencies, and scalp distributions of potentials, no difference was found between spaced vs. no repetition conditions. These results show that smaller amount of attention is allocated to immediately repeated items than to repeated items with delay. Spacing effect could be explained by deficient processing of immediately repeated items.
