Adaptive Method for Finding the Decision-to-React Transition Point

Decision-making is a complex and extended in time process, hidden from direct measurement due to its interim location between the sensory perception of a stimulus and the preparing and execution of a motor reaction. Estimation of the duration of the decision-making process is relevant in fundamental research of cognitive and motor disorders, human-computer interfaces, cybersport and offers a promising avenue for advancing our understanding of decision-making mechanism in diverse populations. Determining the optimal transition point of decision-making processes to the execution of a motor program will allow solving these problems more effectively. In this study, we present an adaptive algorithm for estimating decision duration in a two-alternative forced-choice task. The subjects were presented with colored figures, during each trial the color of the figure has been changed, indicating the end of the preparation period (PP) and requirement for response execution. The task was performed in two conditions: constant (from 0 to 0.8 s) and adaptive PP durations. We found an initial decrease followed by stabilization of reaction time (RT) as the duration of constant PPs increases. The optimal duration of the preparation period was measured as the transition point of two regression lines fitted to the curve. Its location did not differ from mean adaptive PP and RT. Moreover, significant positive correlations were found between the results of the adaptive algorithm and the point of optimality. Thus, the adaptive algorithm localized the mean PP durations to the point of optimality. The proposed algorithm can be applied to determine the duration of decision-making and motor processes in the diagnosis of pathological conditions or used in brain-computer interfaces.