Background: Shinrin-yoku (forest bathing) is a traditional healing practice originating in Japan, wherein individuals immerse themselves in natural forest environments while mindfully engaging their senses (Kotera et al., 2022). In Taiwan, forest bathing or forest healing is the recreation activity in forest to enhance one’s well-being (Chen & Yu, 2023). Recently, the HEAL-ing model, which comprises four core components (Hope, Empowerment, Adaptation, and Life Meaning), has been integrated into forest bathing practices to facilitate deeper, structured psychological healing (Li et al., 2025). This study primarily examines the psychological efficacy of forest healing intervention in Taiwan.

Method: In this preregistered study, we compared the efficacy of a structured "forest healing" intervention against standard forest bathing. The study comprised three groups. The forest healing intervention was administered to two groups: Group A, conducted at the Walami Trail (N = 26; 8 males, 17 females; Mage= 38.5, SD = 17.4), and Group B, conducted at the Alishan National Scenic Area (N = 9; 7 males, 2 females; Mage= 40.0, SD = 13.2). The standard forest bathing control group (Group C) was also conducted at Alishan (N = 10; 8 males, 2 females; Mage= 41.2, SD = 14.7). Participants in the forest healing groups engaged in forest walking while a psychologist facilitated the four components of the HEAL-ing model in small group settings. Conversely, the forest bathing control group engaged in unstructured forest walking, simply enjoying the phytoncides. The Ladder of Happiness (Tang & Li, 2019) was utilized to assess participants' well-being pre- and post-intervention.

Result: For Healing Group A (Walami), scores increased from a pre-test of M = 5.77(SD = 1.41) to a post-test of M = 8.55 (SD = 1.22). For Healing Group B (Alishan), scores increased from a pre-test of M = 5.33 (SD = 2.29) to a post-test of M = 8.78 (SD = 1.79). The Forest Bathing control group (Group C) showed a pre-test score of M = 6.90 (SD = 2.33) and a post-test score of M = 8.00 (SD = 2.78). A 3 X 2 mixed-design ANOVA revealed no significant between-subjects main effect for Group (p = .855). However, significant within-subjects effects were found for Time (p < .001, η2 p = .707) and the Group X Time interaction (p = .010, η2 p = .215), both indicating large effect sizes. Subsequent simple main effects analysis demonstrated that all three groups experienced significant improvements in their well-being dimensions (Healing A: t(21) = 7.46, p < .001, Healing B: t(8) = 5.32, p = .001, Forest bathing : t(9) = 2.91, p = .017). Notably, substantial differences in effect sizes were observed between the experimental and control groups (Healing A: Cohen’s d = 1.59, Healing B: Cohen’s d = 1.77, Forest bathing: Cohen’s d = 0.92).

Discussion: The data demonstrate that the structured HEAL-ing interventions at both Walami and Alishan yielded exceptionally high positive psychological benefits for participants (Cohen's d = 1.59 and 1.77). Although the control group also exhibited improvement—potentially due to the forest bathing (Cohen’s d = 0.92) —the significant Group X Time interaction strongly supports the notion that the specific psychological interventions administered to the experimental groups provide substantial, additional momentum for psychological growth. Emotional benefits were further assessed using the Happiness Life Satisfaction Scale (Li et al., 2025). Results revealed significant differences among the three groups in two distinct indicators: negative emotions (p = .017, η2 p = .177), and motivational autonomy (p = .012, η2 p = .189). Tukey post hoc comparisons showed that negative emotions in Healing Group B were significantly lower than those in the control group, suggesting that the HEAL-ing model significantly mitigates the impact of negative affect. Furthermore, motivational autonomy was significantly higher in both Healing Groups A and B compared to the control group. This indicates that, relative to unstructured forest bathing, the HEAL-ing intervention facilitates a shift in participants from passive environmental exposure to active engagement with nature, aligning with previous literature which asserts that active nature engagement fosters deeper human-nature connections (Kaleta et al., 2025).

TBA