Abstract
We often must inhibit response to one visual stimulus upon seeing another. We asked whether people could inhibit responses in less time when it is more important to do so by offering different levels of reward–points that were later converted into monetary bonuses–for successful inhibition. In our experiments, participants made rapid manual responses to dots appearing on either side of the computer screen. We tested their inhibitory abilities by presenting a square “stop signal” shortly after the dot onset in some trials, indicating that participants must cancel their response to receive reward. We measured the efficiency of response inhibition by estimating the time required for participants to react to the stop signal and cancel their response, namely their stop-signal reaction time (SSRT). In experiment 1, we separated trials with high and low rewards for stopping into different blocks. We found that participants' SSRTs did not vary with the reward for stopping, although participants were significantly slower when responding to the dots in high reward blocks, suggesting that they waited longer in anticipation of potential stop signals in those blocks. We then looked to reduce this anticipation by associating high and low stop rewards with different dot locations and presenting trials with different stop rewards in random order. The unpredictable ordering of reward eliminated the difference between response times to dots in high and low reward locations, and now participants were significantly faster to inhibit their response when reward is high than when reward is low. Our findings suggest that at least in the domain of inhibiting responses to visual stimuli, anticipation of higher reward interferes with more automatic mechanisms we have for improving performance in response to reward.