## 4 Conclusions  
In this study, we found that the response performance of subjects with mild cognitive impairment and dementia were poor compared to normal subjects comprehensively evaluated by reaction time and accuracy rate. Although in the reaction-time analysis, the performance times of the MCI and dementia groups seemed to be shorter than those of the normal group for the same speed level, the accuracy-rate analysis showed poor performance for both the MCI and dementia groups. We observed that these groups reacted randomly by pressing the button when the speed was increased, without considering the accuracy of the object in both the whack-a-mole and hit-the-ball games. Our results, along with those in [6; 7], show that those subjects had significantly poorer performance when measured by simple reaction time and accuracy rate. Moreover, we successfully differentiated these three categories of subjects using our serious games. For the reaction-time analysis, we established that the time-unlimited mode in our experiment is a better method to explain the results. We also found that, even though the two games were designed together to evaluate the reaction performance of the subjects, there were some observable differences in the results of each game. Most subjects had better results with the whack-a-mole game than with the hit-the-ball game. The first reason for this result may be because the hit-the-ball game provides some time for the subject to wait before the ball is on the fairway, which might be related to other cognitive abilities. Further related investigations could be explored in the future. The second reason is because the subjects had to choose between the ball or the meteor ball, which might be related to inhibition ability mentioned by [23], which affect reaction time. This result could also be because the subjects played a similar game (like a whack-a-mole machine at an amusement park (especially in Taiwan)) in the past. This result could, thus, indicate muscle memory that was trained several years ago. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & & **MMSE** & & **One-Way ANOVA** \\ \cline{2-5}
**Game Level** & **Normal (1)** & **MCI (2)** &
\begin{tabular}{c} **Moderate-to-** \\ **Severe (3)** \\ **Mean \(\pm\) SD a** \\ \end{tabular} & **F** & \(p\)**-Value** \\ \hline slow & 0.17 \(\pm\) 0.38 & 0.11 \(\pm\) 0.55 & 0.28 0.51 & 1.213 & 0.301 \\ medium & 0.22 \(\pm\) 0.47 & 0.49 \(\pm\) 0.47 & 0.34 \(\pm\) 0.22 & 9.342 & 0.000 * \\ fast & 0.34 \(\pm\) 0.23 & 0.46 \(\pm\) 0.27 & 0.48 \(\pm\) 0.16 & 6.261 & 0.002 * \\ \hline \hline \end{tabular}  
* SD indicates standard deviation.
* \(p\) < 0.05.  
\end{table} 
Table 11: Response times of subjects at different game level(s) (time-unlimited). Finally, we concluded that the reaction time and accuracy rates can be evaluated using our two serious games while distinguishing between the three different subjects. However, participation of more subjects will be an important factor for future research. We also believe that these research results could be developed to investigate cognitive function for healthy subjects and patients because such results are associated with neural functioning [5; 7]. Therefore, we will also observe potential neural cognitive dysfunction using noninvasive methods such as EEG, MRI, and FMRI with our PC-based serious game. We will also conduct intraindividual variability analysis in future studies to observe the behavior of these subjects. Our hope is that these serious games will be used in the daily life lives of elders to evaluate their performance, followed by and to be followed-up by clinical treatment in the future. [PERSON], [PERSON], [PERSON], and [PERSON] planned and supervised the study, and [PERSON] designed the study. Analyses were performed by [PERSON] All authors have read and agreed to the published version of the manuscript. The authors acknowledge the financial support for this research from the Ministry of Science and Technology Taiwan (grant No.