Résumé
Background and objectives: The reaction time has been known as an important psychophysical method useful for relating mental events to physical measures. Also it has been utilized as an index of sensory, motor and cognitive processes since the inception of the study of behaviour as a laboratory science. So the present study was undertaken to observe and compare the responses of young males and females in predictable and unpredictable environmental setting by employing choice reaction time tasks with constant fore-period of 2 seconds and randomly occurring variable fore-periods of 0.6, 2, 4, 6 seconds. Methods: The choice reaction time tasks were performed for visual and auditory stimuli with constant and variable fore-periods using “Techno Digital Response Time” apparatus. The data were analyzed by Z test. P< 0.05 was considered significant. Results: It was observed that choice reaction times to visual as well as auditory stimuli were lesser in males than in females (p < 0.001) in both constant and variable fore-periods. It was also observed that auditory choice reaction time was shorter than visual choice reaction time. Conclusions: In conclusion, males have shorter reaction time than females. Males react faster than females to changes in the external environment and males are quicker in responding to the unpredictable situations. Choice reaction time (CRT) to auditory stimulus is shorter than that to visual stimulus in both males and females.
Résumé
This study was carried out to investigate the influence of pre-movement tonic contraction on the Contingent Negative Variation (CNV) and Flexor Carpi Radialis (FCR) H reflex between the warning (WS) and response signal (RS) (foreperiod : FP) . Two levels of contraction were designed and the accompanying FCR Electromyography (EMG) was directly returned to the subject to sustain constant contraction. The subjects were 10 normal volunteers. Either small or middle (7.9±5.6% or 16.0±6.3% of the standard FCR EMG) contraction was sustained and the isometric wrist flexion movement was performed as quickly as possible following the RS.<BR>EMG Reaction time (RT) in the small contracting condition was shorter than that in the resting condition (nothing performed during the foreperiod) in almost all subjects, but in the middle contracting condition EMG RT was not similar. The CNV amplitude for the late period of the FP, which was considered to be related to the motor preparation, was larger in the middle contracting condition than in the resting condition, although the small contracting condition was similar to the resting condition. The H reflex amplitude for the late period of the FP tended to be smaller than the control level in the small and middle contracting conditions, but it was not significant. However, in over half of the subjects, whose CNV amplitude for the late period of the FP increased linearly depending on the conditions, the H reflex amplitude was smaller than the control level in both contracting conditions, but it was not linear. These results indicate that the modulation of the EMG RT was not directly associated with the CNV or H reflex amplitudes for the late period of the FP, and a functional difference in the set for the RS between the spinal and the upper level of the central nervous system was present.