Wait for It: Defensive Reactivity and Individual Differences in Contrast Avoidance in the NPU-Reward Task.

Defensive reactivity (startle) is increased during anticipation of temporally unpredictable (> predictable) threat. Startle also seems to be potentiated during reward anticipation, yet how this is affected by temporal unpredictability had not previously been examined. In addition to unpredictability, between-subject differences in how people prepare for and attempt to regulate their response to motivationally salient events might affect defensive reactivity in response to reward. Specifically, contrast avoidance is the self-reported tendency to avoid shifts in emotion, and although typically studied in relation to negative events, it is theorized to apply to positive events, which can set the stage for greater downward shifts in emotion. We used a novel paradigm-the no (N) reward, predictable (P) reward, and unpredictable (U) reward task-to examine the effects of temporal unpredictability and individual differences in contrast avoidance on startle eyeblink and EEG component, the reward positivity (RewP) during anticipation and receipt of rewarding feedback. Sixty-five participants performed the NPU-reward task during EEG and EMG data collection and completed the Contrast Avoidance Questionnaire (Worry version). Startle eyeblinks were potentiated during P versus N reward cues only (i.e., not U > N). By contrast, the RewP was larger for both P and U compared to N reward feedback. In addition, individuals with greater contrast avoidance had larger startle eyeblinks during P compared to U reward inter-stimulus intervals. Therefore, the timing of reward delivery may be important in modulating anticipatory defensive reflexes, and contrast avoidance may interfere with reductions in defense reactivity following rewarding feedback.