Effects of caffeine on recognition.

The present study examined the effects of caffeine on recognition performance after acquisition of conceptual and acoustic tasks. Following a between-subject design, 300 male postgraduate students classified as high or low impulsives received either placebo or one of four doses of caffeine citrate (1, 2, 3, and 4 mg/kg body weight). A double-blind procedure was adopted for drug administration. Caffeine facilitated recognition performance after acoustic acquisition but impaired it after conceptual acquisition in high impulsives. The drug had no influence on recognition performance of low impulsives.