The study on the changes of attentional level : focusing on HP and EMG in the RT task

Abstract

The purpose of this study was to clarify the heart period (HP) changes and the forearm electromyogam (EMG) changes during the fixed (F) and the variable (V) foreperiods of the reaction time (RT) task. Six undergraduate male students of a university were tested under both conditions. In condition F, the mean HP changes showed three components (deceleration-acceleration-deceleration) and the mean EMG changes increased gradually in each foreperiod (4 ,8 and 12 sec) : In condition V, they showed such a wave form corresponding to three foreperiod (4, 8 and 12 sec). The analysis of RTs revealed that in condition F the RTs were significantly faster than those in condition V, and that in condition V the RTs. were faster as the foreperiod increased in length. The mean HP decelerations at the termination of foreperiods were not significantly correlated with the RTs in condition V, but were significantly correlated in condition F (4 and 8 sec). The RTs and the changes observed in the mean. HP and EMG in condition V were interpreted as changes of attentional level produced by the temporal uncertainty and by the motor preparation during foreperiods.