Observing finger movement influences the stimulus-response process of the subsequent non-aiming finger movement.

Aim: The present study investigated whether observing the finger movement influences the stimulus-response process of the subsequent non-aiming finger movement. Methods: Participants directed their eyes to the finger. Three auditory cues with 3 s intervals were provided in each trial. The participants abducted and adducted the index finger in response to the second and third cues; the first response was considered to be the previous response and the second response was considered to be the subsequent response. The time taken for the stimulus-response process was measured via reaction time. Vision was allowed from 0 to 1 s after the start cue of the previous response, after the cue of the subsequent response, or after the cues of the previous and subsequent responses. Results: Online visual information of the stationary finger accelerated the stimulus-response process of the non-aiming finger movement. The acceleration of the stimulus-response process induced by online visual information of the stationary finger was cancelled out by the previous response information, but this cancellation is itself then eliminated by the visual information from the previous response. The visual information from the previous response decelerated the stimulus-response process of the subsequent non-aiming movement, but this deceleration was then itself cancelled out by visual information of the stationary finger immediately before the subsequent non-aiming movement. Conclusion: Taken together, information regarding the previous response functions as noise interfering with the processes contributing to the subsequent non-aiming movement.