Abstract:  Perception of motion-in-depth is essential to guide and modify drive action in interceptive-dominated sports. Tennis players usually exhibit better performance in perception of motion-in-depth. There is considerable evidence for cognitive advantages of sports expertise, but the neural mechanisms of these benefits remain poorly understand. The purpose of this study is to investigate the effect of motor expertise on perception of motion-in-depth by event-related potential (ERP) with expert-novice paradigm. Two groups of volunteers, one comprising 19 expert tennis players with skill level 2 (trained for at least 5 years) and the other 19 novices, participated in the experiment. There were six videos made as the stimuli of the experiment, including four target stimuli (a directly-approaching sphere, a directly-receding sphere, a rotating approaching sphere and a rotating receding sphere) and two non-target stimuli (an expanding circle plane and a contracting circle plane). In each trial, participants watched one video and were asked to identify the target and its motion direction as quickly as they could (if the participant didn’t response in one second, the video ended and it would be considered as a wrong answer). Their reaction time, accuracy and EEG data were recording synchronously when participants completed the cognitive task of motion-in-depth perception. There were a total of 360 trials divided into three blocks of 120 trials each. Each block included 20 repetitions of the six stimuli. ERP data of five electrode sites was selected for further statistical analysis: PO7 and PO8 for P1 and N180, Oz for P2, CPz and Pz for P300. Peak amplitudes (baseline - peak measured) and corresponding latencies were detected in four windows following stimulus onset: 80~160 ms (P1), 160~220 ms (N180), 220~280 ms (P2), and 320~580 ms (P300). Experimental design with 2 factors (direction of motion in depth: approaching vs. away) × 2 factors (rotation pattern: rotating vs. non-rotating) were adopted and further repeated measures of ANOVA in amplitudes and latencies of these ERP components were conducted in group statistical analysis. The results indicated that there was similar processing dynamics in ERP data between expert tennis players and novices. We also detected three main differences between experts and novices: 1) the accuracy of motion-in- deep perception in experts was significantly higher than that of novices; 2) the latency of P1 was significantly longer in “approaching” condition than “away” condition in novices, but experts didn’t show any differences in these two conditions; 3) the latency of P2 was significantly longer in “approaching” condition than in “away” condition in experts, however, signi?cant differences were not found in novices. These results indicated that experts’ better performance in accuracy in perception of motion-in-deep is possibly related to selective attention and pattern recognition. Shorter latency of P2 might be a potential marker to evaluate the ability of perception of motion-in-deep. Additionally, this study will further deepen our understanding for the neural mechanisms of sport expertise.

Key words:  tennis expertise, motion-in-deep perception, expert-novice paradigm, event-related potential