## 3 Results and Discussion  
### Whack-a-Mole  
#### 3.1.1 Accuracy Rate Analysis  
Table 4 shows the accuracy rate and the results of the Kruskal-Wallis test for comparisons of the three groups at different speed levels for accuracy-rate analysis. In the time-limited mode, the Kruskal-Wallis test was used to observe whether the performance of the three groups was different for the three game speed modes. The results show that the three groups had significant differences at medium speed (\(X^{2}=17.147\), \(p<0.05\)) and fast speed (\(X^{2}=10.187\), \(p<0.05\)). The results of the posterior comparison with a Mann-Whitney U test indicated that there was a significant difference between the moderate-to-severe and normal groups (\(p<0.05\)) as well as a significant difference between the MCI and moderate-to-severe groups (\(p<0.05\)) at medium speed. Further, when the speed was fast, the normal and moderate-to-severe groups showed significant differences (\(p<0.05\)), and there was also a significant difference between the MCI group and the moderate-to-severe group (\(p<0.05\)). In the time-unlimited mode, the Kruskal-Wallis test was used to observe whether the three groups were different at the three game speed levels. The results showed that the three groups were significantly different in the fast speed mode (\(p<0.05\)). The Mann-Whitney U test was then used to perform posterior comparisons, and the results showed that, when the speed was fast, there was a significant difference between the moderate-to-severe group and the _normal_ group (\(p<0.05\)). This means that the time-unlimited mode was relatively easy for the normal group but difficult for the moderate-to-severe group. Some subjects in the MCI group performed well, while others performed poorly. Table 5 presents posterior comparisons of the impacts of the different game speeds on test scores using a Friedman Test for the time-limited mode to observe whether game speed was different for the three groups. The results show that the differences of all three groups are significant (\(p<0.05\)). A Wilcoxon signed-rank test was used to perform the posterior comparison, and the results showed that the performance in the moderate-to-severe group was significantly different between the medium to fast, slow to fast, and medium to slow speeds (\(p<0.05\)). The normal group, on the other hand, showed a significant difference (\(p<0.05\)) in performance under the medium to fast and slow to fast speeds but no significant difference in slow to medium speeds; the MCI group also had a similar performance. This means that, for the subjects in the moderate-to-severe group, the three speeds provide three different levels of difficulty. For the normal group, there was no difference in performance between the slow and medium speeds. The MCI group presented a similar performance. In the case of the time-unlimited group, a Friedman test was performed to check if the game speeds of every group of MMSE were significantly different. The results showed that, among the three groups, the normal group and the moderate-to-severe groups had significant speed performance differences (\(p<0.05\)). A Wilcoxon signed-rank test was used to perform the posterior comparison, and the results showed that the performance under slow-to-fast and medium-to-fast speeds in the moderate-to-severe group was significantly