Feedback timing modulates interactions between feedback processing and memory encoding: Evidence from event-related potentials.

Feedback-based learning relies on a procedural learning system driven by reward prediction errors (RPEs). The processing of temporally delayed feedback is supported by brain structures associated with declarative memory processes, but it is still unknown how delayed feedback processing and memory encoding interact. In this study, a subsequent memory paradigm was employed to investigate how the incidental encoding of feedback pictures presented with a short (SD, 500 ms) or long (LD, 6500 ms) delay in a probabilistic learning task affects the event-related potential (ERP) correlate of RPEs (i.e., the feedback-related negativity; FRN). In an ensuing test phase, a surprise recognition memory test for the feedback pictures was conducted. FRN amplitudes measured in the feedback-locked ERPs recorded during the learning phase (FRNpeak) and in the negative minus positive feedback difference wave (FRNdiff) were compared for subsequently remembered and forgotten feedback pictures. Feedback processing as reflected in the FRNpeak was diminished for remembered LD feedback pictures, indicating that delayed feedback processing and memory encoding competed for similar neural processing resources. As evidenced by large FRNdiff amplitudes in the SD condition, the evaluation of shortly delayed feedback strongly relied on the procedural learning system. A complementary model-based single trial analysis was conducted to validate models of the functional significance of the FRN. Consistent with previous studies, feedback-locked N170 and P300 amplitudes were sensitive to feedback delay. In the test phase, memory for LD feedback pictures was better than for SD pictures and accompanied by a late old-new effect, presumably reflecting extended recollective processing.