Errors in motor responding, "rapid" corrections, and false anticipations.

Two experiments investigated the hypothesis that errors in step-tracking were caused by false anticipation of the up-coming stimulus direction. In Experiment 1, eliminating the subject's ability to anticipate temporally did not inhibit error production, suggesting that temporal anticipation is not necessary for error production. In Experiment 2, providing strong spatial expectancies with occasional deviations from the expected direction caused errors to occur, suggesting that errors are caused by false spatial anticipation. The data support the hypothesis that the subjects correct errors by detecting the error upon stimulus onset, a hypothesis that does not require assumptions about the internal monitoring of efference as has been suggested previously.