Poster D88, Monday, March 27, 8:00 – 10:00 am, Pacific Concourse
Lateral occipital complex activation associated with response confidence during forced-choice recognition of novel abstract kaleidoscope images
Michael S. Cohen1, Larry Y. Cheng1, Ken A. Paller1, Paul J. Reber1; 1Northwestern University
Memory studies using stimuli low in conceptual meaning can shed light on fundamental memory mechanisms. We used fMRI to examine brain activity associated with encoding, retrieval, and confidence for novel abstract kaleidoscope images. During study, two images were presented simultaneously in different visual quadrants, following a cue indicating each item’s value. A key brain region during encoding, predicting later recall regardless of value, was lateral occipital complex (LOC). Study runs alternated with yes-no recognition tests for each set of items, with the yes-no test additionally assessing participants’ memory for the quadrant in which the image appeared, and also confidence. Following 6 study/test run pairs, participants completed an unexpected forced-choice test for all stimuli, which also included confidence judgments. High-confidence responses on the forced-choice test, and hits on the yes-no tests, activated a network of frontal and parietal regions typically associated with successful memory retrieval. In addition, confident responses during the forced-choice test were associated with increased LOC activity, relative to novel foil item pairs. While activity was somewhat higher for accurate responses, the increase in LOC activity was apparent even for incorrect high confidence responses, but not for accurate or inaccurate guesses. LOC has previously been associated with object and shape perception, and with successful memory for shapes (e.g., Karanian & Slotnick, 2015). Thus LOC activity may contribute to a subjective feeling of familiarity, which has previously been shown to play a key role in forced-choice tests. Here, familiarity appears to drive confidence as well as accuracy during forced-choice recognition.
Topic Area: LONG-TERM MEMORY: Episodic