Motor behavior couples with several types of environmental information perceived by actors. The phenomenon by which perceptions are distorted by the psychological state of an actor, including motivation, desire, and anxiety, is known as dynamic perception, and many athletes experience this under the psychological pressure of competition. The effects of pressure on the perception of target size before (pre-performance judgement) and after (post-performance judgement) a dart-throwing task and the relationship between size perception and performance outcome in the task were investigated experimentally. Healthy novice female university students (N=20) participated in the experiment. Pressure manipulations included performance contingent competitive cash rewards and comparative others. The results indicated that psychological and physiological stress responses were successfully induced, as indexed by significant increases in state anxiety and heart rate under pressure. Moreover, there were no significant differences in pre- and post-performance size perception between pressure and nonpressure conditions in all participants. However, participants with reduced throwing accuracy under pressure, as compared with non-pressure, perceived the target to be smaller under pressure in post-performance judgement. It is possible that attentional change including conscious processing and distraction, as well as kinematic changes, led to a decrement of motor skills performance that might have caused perceptual distortion under pressure. Exploratory multiple regression analysis to identify factors leading to perceptual distortions of target size under pressure indicated that participants reporting larger trait anxiety judged the target to be smaller in only preperformance judgement.
