Mar 08

CNS 2016 Abstract

High value leads to improved explicit recollection, but reduced implicit memory, when learning kaleidoscope images

Michael S. Cohen1, Larry Cheng1, Ken A. Paller1, Paul J. Reber1; 1Northwestern University

Recognition judgments typically rely on MTL-dependent explicit memory, but in some cases, participants can make accurate guesses seemingly driven by implicit memory (e.g., Voss et al. 2008). These “implicit recognition” effects provide a rare opportunity to observe interactions between implicit and explicit memory systems, but have also proven somewhat challenging to study. Here, we use a value-directed recognition (VDR) paradigm to elicit recognition responses that either depend on explicit memory or benefit from a contribution of implicit memory. Two novel kaleidoscope images were shown simultaneously in two different spatial quadrants during study, one marked high-value and one low-value, in blocks of 16 stimuli. After each study block, participants performed source memory (quadrant) and yes-no recognition to assess explicit memory. Explicit memory was better for high point-value items, likely due to increased encoding effort. After all 7 study blocks, participants also completed a forced-choice recognition memory test, previously shown to be more sensitive to contributions of implicit memory. Here, there was an interaction between value and confidence, with low point-value items tending to produce higher levels of accurate guessing on the forced-choice test than high-value items. Thus, previously reported effects of VDR—improved explicit memory for high-value items—extend from verbal memory to novel, non-verbalizeable stimuli, while more robust implicit memory contributions can be elicited from items marked low-value. This approach will enable further investigation of the neural basis of interactions between these two forms of memory, and of when implicit memory representations inform guesses on recognition memory tests.

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