RESUMEN
The measure of visual reaction time has been used to evaluate the processing speed of Central Nervous System and the co-ordination between the sensory and motor systems. As the reaction time is influenced by different factors, the impact of psychological stress, gender effect and the colour of objects in modulating the reaction time have been investigated in this study. 32 male and 38 female medical students in the age group of 18-21 yrs participated as subjects. It was observed that a) the males had a visual reaction time lesser than their female counterparts b) response latency for green colour was lesser than that for red in both the males and the female subjects and c) psychological stress resulted in a significant decline in the reaction time to green colour in males. The longer reaction time in females could be due to the effect of female sex hormones, which reduced the velocity of nerve impulse and increased the synaptic delay. Green colour evoked a faster response due to its stronger stimulation on the visual receptors.