ABSTRACT
In three experiments the effects of instructed muscle tension on reaction time (RT) and movement time (MT) are explored with regard to some other variables affecting RT. Two conditions of instructed muscle tension were compared. In one subjects had to relax the relevant muscle groups fully, being taught to do so by biofeedback. In the other condition they had to strain the relevant muscles optimally. Relaxation prolonged RT by some 40-60 msec but did not affect MT. The effect interacted with that of foreperiod duration (Experiment 1), showed a second-order interaction with foreperiod duration and relative S-R frequency (Experiment 2), and was additive to those of S-R compatibility and signal degradation (Experiment 3). Application of the additive factor logic to the results suggests four processing stages, the nature of which are discussed.
