title: The effects of different instructions for preparatory muscle tension on simple reaction time.
abstract: The effects of preparatory weak muscular contraction (pre-tension) have been investigated in a number of previous studies using tasks with either simple or choice responses to measure the reaction time (RT). These studies suggested that optimal pre-tension performed prior to a motor response tends to shorten the RTs. Using a simple RT task in which participants performed a grip response to a visual stimulus, the present study compared the RTs between two pre-tension conditions (self-selection and constraint) to investigate the effects of different instructions for pre-tension. Under the self-selection condition, participants were asked to determine their optimal pre-tension levels while attempting to give responses as fast as possible. Under the constraint condition, the participants developed a pre-tension at a target force determined by the experimenter. The target force was set at the same level as the pre-tension level maintained under the self-selection. Despite the fact that the pre-tension level manipulated was the same for both conditions, the RTs were significantly shorter under self-selection than under constraint. Moreover, the present study showed a positive correlation coefficient between the proportion of shortening in RT and the variation of pre-tension level. This indicated a performance trade-off between the stability of pre-tension and RTs. The result suggests that shorter RTs that occur under self-selection are primarily mediated by mental factors, such as attention allocation, rather than by the effects of peripheral muscular preparation.
authors.affiliation: Department of Kinesiology, Tokyo Metropolitan University, 1-1 Minami-Ohsawa, Hachioji, Tokyo 192-0397, Japan. kkimura@comp.merto-u.ac.jp
authors.forename: Ken
authors.initials: K
authors.lastname: Kimura
authors.forename: Kuniyasu
authors.initials: K
authors.lastname: Imanaka
authors.forename: Ichiro
authors.initials: I
authors.lastname: Kita
mesh_terms: D000293:Adolescent; D000328:Adult; D001288:Attention; D004576:Electromyography; D018737:Hand Strength; D006801:Humans; D007537:Isometric Contraction; D008297:Male; D011597:Psychomotor Performance; D011930:Reaction Time; D012718:Set, Psychology