Event-related brain potential (ERP), heart rate (HR), and blood pressure (BP) responses were examined during the 6s foreperiod of a choice-reaction task. Low and high trait-anxious males were required to make same/different judgements based on the similarity of two successively presented visual patterns. The pitch of a warning tone, presented at the beginning of the foreperiod, indicated whether speed or accuracy was to be emphasized on that trial. In different conditions, subjects received either a monetary reward or aversive noise, depending on their performance. Two clusters of parallel variations were observed in the foreperiod: (1) speed/accuracy instructions affected the amplitude of the CNV and, in interaction with anxiety group, the initial decreases in HR and diastolic BP; (2) type of reward, in interaction with speed/accuracy instructes, affected the amplitude of the P300 and PSW, the mid-interval HR acceleration, and subse-quent increases in diastolic and systolic BP. A correlational analysis showed a close relationship between changes in HR and BP, whereas no relationship was evident between changes in ERPs and changes in HR and BP.