# Perceptual Judgments for Table Tennis Serve Recognition: An Event-Related Potentials Study
## 3 Results
### ERPs Results  
Waveforms and topography maps are shown in Figures 3 and 4, respectively. The electrophysiological components including C1 (40-80 ms), P1 (80-150 ms), N1 (90-160 ms) and P3 (300-500 ms) were induced in different brain regions when participants recognized the types of serves. \begin{table}
\begin{tabular}{c c c c c} \hline \multirow{2}{*}{**Groups**} & \multirow{2}{*}{**N**} & **Target Stimuli (M \(\pm\) SD)** & **Standard Stimuli (M \(\pm\) SD)** \\ \cline{3-5}  & & **RT (ms)** & **ACC (\%)** & **RT (ms)** & **ACC (\%)** \\ \hline Table tennis athletes & 15 & 461.225 \(\pm\) 40.099 & 98.3 \(\pm\) 2.1 & / & 93 \(\pm\) 7.7 \\ Undergraduates & 15 & 507.875 \(\pm\) 55.307 & 77.8 \(\pm\) 15.1 & / & 79.1 \(\pm\) 19.4 \\ \hline \end{tabular}
\end{table} 
Table 1: Behavioral results for target stimuli and standard stimuli: reaction time and accuracy rate of both table tennis athletes and undergraduates. Figure 3: Grand average waveforms for correct responses of the two groups of participants. They were instructed to press a button whenever an infrequent target stimulus appeared in a series of frequent standard stimuli. The left waveforms of central sites (Cz, C3 and C4) were indexed by the responses to target stimuli, while the right of occipital sites (Oz, O1 and O2) were by standard stimuli. C1 (window from 40 to 80 ms): The peak latency and amplitude of C1 were analyzed at occipital sites (Oz, O1 and O2) in a 2 (groups) \(\times\) 2 (stimuli) \(\times\) 3 (electrodes) repeated-measures ANOVA. The results indicated a significant groups \(\times\) stimuli \(\times\) electrodes interaction (F (3.315, 92.809) = 6.334, \(p\) = 0.000, \(\eta\)p2 = 0.184; F (3.484, 97.546) = 3.550, \(p\) = 0.013 \(<\) 0.05, \(\eta\)p2 = 0.113). Significant differences for standard stimuli between groups were found by simple effects analysis, and the results revealed that table tennis athletes  
Figure 4: Scalp topographies distributions from the two groups of participants were illustrated by the mean C1, P1, N1 and P3 amplitude and latency. The distinct patterns from each component separately evoked by target stimuli and standard stimuli at the peak time point were noted. Color bar indicates mean signal amplitude in microvolts. (48.8 ms, \(-\)2.368 \(\mu\)v) showed a shorter C1 peak latency and larger amplitude than undergraduates (62.4 ms, \(-\)1.202 \(\mu\)v). P1 (window from 80 to 150 ms): Peak latency and amplitude of P1 were analyzed at occipital sites (Oz, O1 and O2) in a 2 (groups) \(\times\) 2 (stimuli) \(\times\) 3 (electrodes) repeated-measures ANOVA. The results indicated a significant groups \(\times\) stimuli \(\times\) electrodes interaction (F (4.128, 115.577) = 6.334, \(p=0.000\), \(\eta\)p2 = 0.248; F (2.717, 76.081) = 3.848, \(p=0.015\) < 0.05, \(\eta\)p2 = 0.121). Significant differences for standard stimuli between groups were found by simple effects analyses; the results revealed that table tennis athletes (130.0 ms, 5.617 \(\mu\)v) showed a longer P1 peak latency and larger amplitude than undergraduates (115.2 ms, 3.536 \(\mu\)v). N1 (window from 90 to 160 ms): Peak latency and amplitude of P1 were analyzed at central sites (Cz, C3 and C4) in a 2 (groups) \(\times\) 2 (stimuli) \(\times\) 3 (electrodes) repeated-measures ANOVA. The results indicated a significant groups \(\times\) stimuli \(\times\) electrodes interaction (F (2.997, 83.922) = 5.702, \(p=0.001\), \(\eta\)p2 = 0.169; F (3.069, 85.935) = 4.441, \(p=0.006\) < 0.01, \(\eta\)p2 = 0.137). Significant differences for target stimuli between groups were found by simple effects analysis, and the results revealed that table tennis athletes (127.8 ms, \(-\)6.232 \(\mu\)v) showed a longer N1 peak latency and larger amplitude than undergraduates (102.0 ms, \(-\)3.494 \(\mu\)v). P3 (window from 300 to 500 ms): Peak latency and amplitude of P3 were analyzed at central sites (Cz, C3 and C4) in a 2 (groups) \(\times\)2 (stimuli) \(\times\) 3 (electrodes) repeated-measures ANOVA.