Poster B43, Sunday, March 26, 8:00 – 10:00 am, Pacific Concourse
ERP Evidence for Conflict in Contingency Learning
Chris Blais1, Peter S Whitehead2, Gene A Brewer1; 1Arizona State University, 2Duke University
The proportion congruency effect refers to the observation that the magnitude of the Stroop effect increases as the proportion of congruent trials in a block increases. Contemporary work shows that proportion effects can be driven by both context and individual items, and are referred to as context-specific proportion congruency (CSPC) and item-specific proportion congruency (ISPC) effects, respectively. The conflict-mediated Hebbian learning account posits that these effects manifest from the same mechanism, while the parallel episodic processing model posits that the ISPC can occur by simple associative learning. Experiment 1 examines the neural correlates of the CSPC and finds that the N2 over frontocentral electrode sites approximately 300 ms after stimulus onset predicts behavioral performance. There is a strong consensus that this N2 signal is associated with conflict detection in the medial frontal cortex. Experiment 2 assesses whether the same qualitative electrophysiological pattern of results holds for the ISPC. We find that the spatial topography of the N2 is similar but slightly delayed with a peak onset of approximately 330 ms after stimulus onset. Taken together, the results from both experiments indicate that a single common mechanism, conflict-mediated Hebbian learning, drives both the ISPC and CSPC.
Topic Area: EXECUTIVE PROCESSES: Monitoring & inhibitory control