## 3 Results
### fNIRS Results  
Figure 4 shows the courses over time of the mean fNIRS signals that were measured during the 20 s pre-task baseline period and the 105 s 1-back tasks. Figure 5 displays the mean values of oxy-Hb for each of the four 105 s time segments in the 1-back task. The repeated ANOVA of 2 (group: experimental group, control group) \(\times\) 2 (time measurement: pre-test, post-test) \(\times\) 4 (time segment: 1, 2, 3, 4) revealed the following main effects to be (marginally) significant: time measurement, \(F(1,\) 15) = 8.12, \(p=0.012\), \(\eta_{\mathrm{p}}{}^{2}=0.35\), and time segment, \(F(3,\) 45) = 2.56, \(p=0.067\), \(\eta_{\mathrm{p}}{}^{2}=0.15\). The interaction of time measurement and group was also significant, \(F(1,\) 15) = 14.46, \(p=0.002\), \(\eta_{\mathrm{p}}{}^{2}=0.49\). No other effects or interactions reached significance.  
Figure 4: The courses over time of the mean oxy-Hb signals in the left lateral frontal lobe that were measured during the 20 s pre-task baseline period and the 105 s 1-back tasks. The fNIRS signals of four task blocks were averaged at the same sampling point along 125 s (totally 6250 sampling points) to obtain the time series figure for improving the signal-to-noise ratio (SNR).  
Figure 5: The mean values of oxy-Hb for each of the four 105 s time segments in the 1-back task.  
To examine these interactions, the experimental group and the control group in oxy-Hb values were analyzed by separate ANOVAs, see Table 5. For the experimental group, both the main effects of time measurement and of time segment were significant, \(F(1,7)=50.54\), \(p<0.001\), \(\eta_{\text{p}}{}^{2}=0.88\), \(F(3,\) 21\()=3.98\), \(p<0.05\), \(\eta_{\text{p}}{}^{2}=0.36\). The time measurement and time segment interaction was not significant, \(F(3,21)=2.21\), \(p=0.12\), mainly due to the pre- vs. post-test significant differences for 1 st, 2 nd, and 3 rd time segments, \(F(1,7)=17.27\), \(p<0.01\), \(\eta_{\text{p}}{}^{2}=0.71\), \(F(1,7)=9.54\), \(p<0.05\), \(\eta_{\text{p}}{}^{2}=0.58\), \(F(1,7)=18.68\), \(p<0.01\), \(\eta_{\text{p}}{}^{2}=0.73\). Although there was no significant difference between pre- and post-test conditions in mean oxy-Hb values for the 4 th time segment, \(F(1,7)=0.12\), \(p=0.74\), the similar trend was reflected in Figure 4.  
For the control group, in contrast, the main effects of time measurement and of time segment were not significant, \(F(1,8)=0.32\), \(p=0.58\), \(F(3,24)=0.37\), \(p=0.75\), as was the time measurement and time segment interaction, \(F(3,24)=0.19\), \(p=0.88\). Further analyses revealed that there were no significant pre- vs. post-test differences for the four time segments, \(ps>0.05\).  
The mean values of oxy-Hb in both pre-test and post-test were normalized, and the difference value from pre-test to post-test was calculated as \(\delta Z_{\text{oxy-Hb}}=Z_{\text{post oxy-Hb}}-Z_{\text{pre oxy-Hb}}\). \(\delta Z_{\text{hit}}\) and \(\delta Z_{\text{flase-alarm}}\) were calculated in the same way. Then, the correlation analysis was conducted. A positive correlation was observed between \(\delta Z_{\text{hit}}\) and \(\delta Z_{\text{oxy-Hb}}\), \(r\) (17) = 0.58, \(p<0.05\), and a negative correlation was found between \(\delta Z_{\text{flase-alarm}}\) and \(\delta Z_{\text{oxy-Hb}}\), \(r\) (17) = \(-0.56\), \(p<0.05\). This result indicated the consistency of behavioral and neural changes.