The effects of fatigue on the control of a coincident timing response.

The present study investigated the extent to which fatigue influenced the usage of feedback by Ss to make corrections during coincident timing responses. Sixteen college males watched a .01-sec timer and attempted to knock over a barrier at the moment that the sweep hand reached 500 msec. All Ss were given 50 trials of practice on each of four consecutive days. The fatigue group's performance was immediately preceded by a response-specific local fatigue (dynamic exercise). To insure the maintenance of a high level of fatigue throughout practice, the fatiguing exercise was interspersed with the coincident timing task. The control group performed the same exercise as the fatigue group but without any resistance. Schmidt's (1972) index of preprogramming (IP) was calculated for each day in order to determine the level of feedback involvement in controlling the movement. Fatigue did not influence the accuracy with which Ss responded or the rate that they learned. However, the results indicated a relatively high and stable IP throughout all trials with the IP for the fatigue group higher than that of the control, suggesting a preference by these Ss for a programming mode of control.