Table 5. Subjective feeling for intervention in the Brain Age and Tetris groups.

	Brain Age group		Tetris group
	(9M/7F)		(9M/7F)
	Mean	SD	Mean	SD	Effect size (d)	p-value
Motivation	6.25	1.43	6.33	1.45	0.05	0.87
Fatigue	3.43	1.63	3.53	1.35	0.06	0.86
Satisfaction	6.56	1.82	6.46	2.06	0.05	0.89
Enjoyment	6.51	2.26	6.40	2.36	0.05	0.78

No significant difference was found between Brain Age and Tetris groups (two sample t-test, p>0.10). Effect size estimates were calculated using Cohen's d. d = 0.20 is regarded as a small effect, d = 0.50 as a medium effect, and d = 0.80 as a large effect. M, number of men; F, number of women; Motivation, motivation of playing the video game during the intervention period; Fatigue, fatigue during the intervention period; Satisfaction, satisfaction of the intervention during the intervention period; Enjoyment, enjoyment of the video game during the intervention period; SD, standard deviation.