Spectators lead to overconfidence and risk-taking in males in a motor task.

We often perform motor tasks in front of other people, and this may help or hinder our performances. Previous research mainly focused on changes in motor performance, and less is known about spectator influences on performance predictions. An accurate performance prediction in motor tasks is important, as it supports optimal performance. The present study examined whether being observed by spectators influences not only performance, but also performance predictions in a motor task. We tested 341 participants on a speeded cup-stacking task in a within-subjects design: co-acting (performing concurrently with others) versus performing alone in front of an audience. In half of the trials, participants predicted how many cups they would be able to stack in the upcoming trial. Overconfidence, by predicting performances that were too high, resulted in failed trials. Being watched by others led to motor performance decrements. Both males and females left a safety margin in their performance predictions in the co-acting condition. Being watched by others led males to increase their overconfidence and failure rate, whereas females left a safety margin in their predictions, maintaining a stable failure rate in front of spectators. Our results indicate that spectators not only influence motor performance, but also performance predictions.