This study investigated the effect of the allocation of attentional resources on event-related potentials (ER-Ps) and cardiovascular responses during a dual-task situation in which an avoidance task and a reward task were coupled. For the avoidance task, subjects were able to avoid an aversive shock that followed a target tone by pressing a button. For the reward task, subjects were asked to detect the direction of an arrowhead presented on the display screen and were rewarded for rapid, accurate reaction times. The 31 participants were divided into two groups based on their subjective impression of attention distribution between the avoidance and the reward task. Participants in the first group were motivated more by the avoidance task (AVD; n = 18), whereas those in the second group were motivated more by the reward task (RWD; n = 13). The ERPs to nontarget and target tones, ECG, systolic blood pressure (SBP), and diastolic blood pressure (DBP) were analyzed in the dual-task situation. The results indicated that the amplitudes of NI to target and non-target tones, and of N2 to the target tone were larger in the avoidance (AVD) group than they were in the reward (RWD) group. The AVD group had higher blood pressure than did the RWD group during the aversive periods. However, there were no significant group differences in the mean RTs for avoidance and reward tasks, and participants in both groups reported similar subjective evaluations of their mental workloads. The results suggest a vigilant coping strategy that selectively focus attention to threatening information as illustrated by NI and N2 changes may intensify psychophysiological arousal under stress. (c) 2006 Elsevier B.V. All rights reserved.