The controllability of aversive and neutral pictures: an event-related potential study.

Control over physically aversive stimuli may reduce stress, arousal and physiological responses to these stimuli. Nonetheless, avoidance of emotionally aversive stimuli/excessive attempts to control negative emotion might alternatively increase the salience of these stimuli. Here, we used a novel paradigm to examine the effect of controllability on the processing of aversive and neutral pictures (using the late positive potential, LPP) and response uncertainty (using the post-imperative negative variation, PINV). Participants (n = 48) were told that they could press a button to terminate the presentation of an aversive or neutral picture, but this was only true during some blocks of the experiment and not others. Results showed that the LPP was larger for control compared to no control blocks and that this was driven by larger LPPs to aversive pictures during the first control block, but only for participants who had started the task in a no control block. Therefore, knowing that aversive stimuli might not always be controllable (i.e., a prior experience of uncontrollability) appears to increase the motivational salience of these stimuli once control becomes possible. In addition, uncontrollability increased both the early and late PINV, and the late PINV was larger for the second compared to the first control block. As such, the current study provides the first evidence that the PINV can be elicited using aversive and neutral pictures and suggests functional differentiation between the early and late portions of the PINV. Results support the utility of this novel paradigm for examining control over emotional stimuli.