Electrophysiology of Non-Conscious Memory Contributions to Free Recall

RM 208

Recollection of memories can be driven both implicitly or explicitly. Explicit memories can be called to mind, expressed in words, and assigned a time frame, whereas implicit memories involve an unconscious registration and storage of information. For instance, in a free recall task, individuals correctly recall and recognize words that were studied beforehand (hits); however, on other occasions individuals correctly recall words but fail to recognize that these words were from a list studied beforehand (misses). Thus, these recognition failures or “misses” represent a unique paradox in recall. The mechanism that drives the production of memory failures within free recall is poorly understood, and the current work was designed to assess the reliability of previous preliminary findings that ascribed this phenomenon to implicit memory. Participants first studied a list of words during an encoding phase. In a subsequent memory test, participants were presented with a new list of semantically associated words intermixed with non-associate words during a recall task, and then assessed for item recognition while electroencephalogram (EEG) was recorded. Participants performed above chance-level in memory recall & recognition but results from EEG diverged from prior findings suggesting an implicit memory mechanism supporting recognition misses in free recall. These results are discussed in the context of factors in experimental design differences that can lead to discrepant findings among laboratories.