2022 年 67 巻 p. 859-877
We examined the effects of postural intervention using a “risshin chair” (an upright support seat assisting a zazen-like posture) on posture maintenance, classroom time perception, implicit affect, mental health, and life meaningfulness in an actual high school setting. Twenty-seven second-grade high school students (15 girls and 12 boys; Mage = 16.93 years, SD = 0.27) sat on either a conventional chair or a risshin chair in A-B-A order for approximately four weeks in total. One-way ANOVA revealed that (a) mental health score was highest in the intervention period than in the pre- or post-intervention period (p < .001; p = .002), and that (b) the living in the present moment score was higher in the intervention period than in the pre-intervention period (p < .001). Twocondition within-participant serial mediation analysis also showed that the use of the risshin chair affected mental health and daily meaning in life through a higher level of postural improvement and a faster level of classroom time perception change (indirect effect = 0.27, 95% CI [0.02, 0.74]; 0.28, 95% CI [0.04, 0.66]). The need for examining the effectiveness of longer-term postural interventions was discussed.