EFFECTS OF CAFFEINE ON PERCEPTUAL JUDGMENT

The present study examined the effects of caffeine on the estimation o f felt width of blocks employing haptic presentation. Following a betw een-subject design, 160 male postgraduate students classified as high or low impulsives received either placebo or one of four doses of caff eine citrate (1, 2, 3 and 4 mg/kg body weight). A double-blind procedu re was adopted for drug administration. Caffeine produced differential effects on the performance of high and low impulsives, facilitated pe rformance (decreased error in perceptual judgment) in high impulsives but had no influence on the performance of low impulsives. The dose-re sponse trends also followed different patterns in the two groups of su bjects.