Event-related potential (ERP) was used to examine the interactions between working memory and se- lective attention. We combined two unrelated tasks, one requiring working memory and the other se- lective attention, which were performed by some undergraduates. The ERP results revealed that both congruent and incongruent stimuli in the selective attention task evoked an N400 component, reaching the peak point at around 500 ms. The N400 evoked by incongruent stimuli was more negative than that of congruent, which indicated the difference of semantic N400. Furthermore, working memory load had a significant influence on the N400 evoked by selective attention task in parietal region. And working memory load showed difference in the ERPs of working memory retrieval in central and parietal regions. The ERPs of probe under high working memory load were more positive from 350 to 550 ms post-stimulus; however, stimulus type of selective attention had no influence on working memory re- trieval. The present study shows that working memory does not play a major role in the selective at- tention, especially in ignoring distracter, but it influences the performance of the selective attention as the background. The congruency of target and distracter in the selective attention task does not influ- ence the working memory retrieval.
ERP dissociations between implicit and explicit memory have been confirmed by a large amount of evidence in theories of human memory. However, similarities between the two forms of memory have scarcely been studied. A possibility is that while implicit memory and explicit memory have independ- ent components, they might additionally have shared components. To explore this question, an ERP experiment was conducted with a study-to-test paradigm, in which participants performed a "shallow" (color) study task or a "deep" (pleasant) study task, followed by either a lexical decision (implicit) test (Section 1) or a recognition (explicit) test (Section 2). An interference task was performed concurrently with either the encoding or the retrieval phase of the memory task for encoding interference condition or retrieval interference condition. We compared ERP signatures of implicit and explicit memory as a function of depth of processing or interference. Under the action of the same variables, 300―500 ms old/new ERP effects of implicit and explicit memory showed the same trend. These effects maybe all link with a perceptual representational system. 500―700 ms old/new ERP effects of the two memories were dissociated. They may probably reflect voluntary and involuntary recollection respectively. These results suggested that implicit and explicit memories are not completely independent of each other, but have both independent and shared components.
