On observing another person's actions: influences of observed inhibition and errors.

It was investigated whether an observer would simulate another person's inhibitory and error processes. Two participants sitting next to each other performed a stop signal task in which they occasionally had to try and inhibit their response when indicated to do so by a stop signal. They could either successfully stop the response or fail to stop and, thereby, make an error. An aftereffect of the other person's successful action inhibition and error was obtained: The participants became slower and more accurate when they observed the other person make an error on the previous trial and when they observed a successful stop. The results suggest that observing another person successfully inhibit an action or make an error evokes processes similar to those that occur when these behaviors are produced.