This study attempted to examine if there was a corresponding attentional narrowing with increases in arousal from a low to a high level on dual task. Thirty male college students, who were subjected to each of three levels of psychological stress, were randomly assigned to three equal sized groups; i.e., Low Stress, Middle Stress and High Stress Groups. In this experiment a dual task method was used, which incorporated Main Task, Peripheral Task and Irrelevant Task. Subjects were requested to perform a perceptual-motor task as Main Task whi1e simultaneously discriminating the light located in the visual periphery called Peripheral Task. Then, the subjects were asked to recall the auditory stimuli which were presented during the performance of the Main and Peripheral Tasks. Recall method of this Irrelevant Task was not informed to subjects before this experiments. The results indicated the inverted-U relationship between arousal level and task performance on the Main Task. On the Peripheral and Irrelevant Task, Low Stress Group indicated the best performance, followed by Middle Stress Group and then, High Stress Group. These findings supported the attentional narrowing phenomenon. The results were discussed in terms of range and stability of me utilization. It is suggested that the attentional style of Low Stress Group would be active distraction and High Stress Group would be passive distraction. Consequently, the difference of attentional style between low and high arousal state appears to be necessary to explain the inverted-U hypothesis.