Investigating interactions between working memory and long-term memory systems using the Hebb repetition effect
K.L. Gigler & P.J Reber
Long-term working memory (LTWM) reflects an interaction between working memory (WM) and long-term memory (LTM) systems in which effective WM capacity is expanded for experts due to knowledge representations in LTM. In the laboratory, this interaction can be studied with the Hebb repetition effect, where performance on a span-based WM task improves when a target sequence is presented repeatedly. Here the Hebb effect was examined using a visuospatial WM task in which cues were presented in four different spatial locations and participants attempted to reproduce presented sequences, with one target sequence presented repeatedly. Across three experiments, participants with explicit knowledge of the repeating sequence exhibited higher effective span for the repeated sequences. When the presented sequence started at the beginning of the sequence, the repetitions were obvious and the Hebb effect was obtained. When repetitions started from varying points within the sequence, only a subset of participants recognized the sequence. Participants who explicitly recognized the repeating sequence exhibited the Hebb WM expansion effect. Participants with higher WM capacity were more likely to recognize the sequence. Neuroimaging results highlight the interactions between LTM and WM systems. These results indicate the operation of a feedback loop whereby higher initial WM leads to increased knowledge in LTM, enhancing effective WM via LTWM, as seen with the Hebb effect. These results provide insight into why high WM capacity may lead to faster acquisition of expertise in complex domains.