Relationship between the processing time required for movement by initiation instructions and the process of behavioral expression.

Abstract

The nature of the human mind is a long-standing question that has eluded definitive answers from varous scientists, but the truth has yet to be elucidated. One of the phenomena that has been studied as a sign of consciousness is the readiness potential (RP), which is observed prior to human voluntary actions. It has been found that RP occurs 500-800 ms a person intentionally acts, earlier than their conscious will for initiate the action. We conducted an experiment with different instructions for movement initiation and divided the time until movement onse into three phases: time of deciding (T1), time of planning movement (T2), and time of actual movement (T3). Participants performed tasks that required all of T1, T2, and T3, tasks that required only T2 and T3, and tasks that solely required T3. By comparing the onset times of each task, we found that T1 and T2 lasted approximately 25 ms, while T3 lasted approximately 360 ms. We observed a correlation between the duration of ”T1 and T2”, and a larger maximum amplitude of RP, indication that shorter T1 and a longer T2 were associated with larger RP amplitudes in movements similar to those in the present experiment. Moreover, we observed that task difficulty affected the maximum amplitude of RP, suggesting that harder tasks resulted in larger RP amplitudes and, therefore, shorter T1. This suggests the possibility that unconscious decision-making and preparatory processes related to task difficulty.