Abstract
[Purpose] The purpose of this study was to investigate the influence of inter-onset interval (IOI) shift below the threshold of conscious recognition on the control of reactive movement. [Subjects and Method] Fourteen healthy subjects performed the reaction time tasks, raising their right ankles in response to auditory stimuli under three conditions: 1) periodic auditory stimuli with IOI of 1500 ms, and only the last stimulus interval shifted to 2) 1425 ms and 3) 1200 ms, in successive stimulus sequences with an IOI of 1500ms. Electromyographic reaction times (EMG-RT) of the last stimulus were compared among the three conditions. [Result] EMG-RT of condition 3 was significantly delayed compared to conditions 1 and 2. There was no significant difference between conditions 1 and 2. [Conclusion] Periodic rhythmic stimulation is predicted to have some time width, and reactive movement can be performed without delay in conditions of an IOI shift below the threshold of conscious recognition.
