Attention and Emotional States during Horticultural Activities of Adults in 20s Using Electroencephalography: A Pilot Study

Psychophysiological and psychological responses of touching plant behavior by tactile stimulation according to the foliage type

Urbanization-related stress has spurred interest in natural therapies, such as horticultural therapy, which leverages multisensory exposure to plants to enhance well-being through physical, psychological, and cognitive benefits. This study aimed to measure and compare the psychophysiological and psychological responses to tactile stimuli through plant contact based on the foliage type. Thirty adults (average age: 24.86 ± 2.68) participated in the study, and the foliage was categorized into four groups: soft (e.g., Stachys byzantina, Adiantum raddianum, and Asparagus plumosus var. nanus), smooth (e.g., Peperomia obtusifolia, Ficus benghalensis, and Epipremnum aureum), stiff (e.g., Chamaeshparis thyoides Red Star, Platycladus orientalis, and Cupressus macrocarpa), and rough (e.g., Rhapis excelsa, Nephrolepis cordifolia 'Duffii', and Ardisia pusilla 'Variegata') plant groups. The participants touched the plants for 90 s, and the concentration of oxyhemoglobin (oxy-Hb) in the prefrontal cortex (PFC) was measured using functional near-infrared spectroscopy (fNIRS). Additionally, a semantic differential method (SDM) evaluation tool was used to assess the psychological responses of each treatment group. When comparing the four tactile treatment groups (soft, smooth, stiff, and rough), the oxy-Hb concentration in the PFC area was lowest during tactile stimulation of smooth plants and highest during soft plant stimulation. Sex-based comparison of oxy-Hb concentrations showed significant differences in the overall PFC area for all four tactile treatment groups in males (p < 0.001). Specifically, when touching soft plants, the oxy-Hb concentration in females was significantly lower than that in males (p < 0.001). According to the SDM, the tactile stimulation of soft and smooth plants elicited the most relaxation, comfort, and favorable responses (p < 0.001). When touching smooth plants, the oxy-Hb concentration of the participant was the lowest, and according to the SDM, they reported the most soothing response. Summarily, the participants in the smooth plant group exhibited a trend of decreased oxy-Hb concentrations and concurrently experienced a sense of psychological stability. We established those tactile stimuli based on foliage texture resulted in different psychophysiological and psychological responses depending on the plant treatment group and sex.

Promoting adult health: the neurophysiological benefits of watering plants and engaging in mental tasks within designed environments

BACKGROUND

Indoor, sedentary lifestyles have disconnected individuals from nature, necessitating interventions to reestablish this bond. Performing horticultural activities, such as watering houseplants, offers a potential solution. This study sought to determine how participating in horticulture activities affected adults' cognitive and emotional moods.

METHODS

We compared the benefits of watering houseplants (a gardening task) to those of standing while performing a computer task (a mental task). Chinese participants, aged 20 to 21 years, were recruited; their physiological and psychological reactions were measured using electroencephalograms, blood pressure assessments, and psychological assessments.

RESULTS

Fifty participants were included. Watering indoor plants significantly reduced blood pressure, without affecting pulse rate. During the plant watering task as opposed to the mental activity, more dramatic different patterns of very high alpha and beta brainwave activity were identified. Participants reported increased happiness following gardening activities.

CONCLUSIONS

The findings of this study highlight the substantial relaxation benefits, both mental and physical, associated with the simple act of watering indoor plants.

Horticultural therapy for stress reduction: A systematic review and meta-analysis

Introduction

Horticultural therapy has been increasingly accepted as a non-pharmacological stress reduction treatment. Previous studies have demonstrated its therapeutic effects, with the effect varying according to the populations, settings, and interventions of horticultural therapy. This study aimed to provide a comprehensive review of the current literature regarding the effectiveness of horticultural therapy in reducing stress.

Methods

We selected databases including PubMed, Cochrane Library, Embase, Web of Science, China National Knowledge Infrastructure, and VIP Data as our data source, and the original search was completed in January 2023.

Results

Our results showed significantly increased effects of horticultural therapy on psychological indicators compared to a control group, but an insignificant effect on physiology indicators. The result of the subgroup analysis demonstrated that the stress-reducing effects of horticultural therapy were related to the characteristics of the population and indoor and virtual areas were the most effective setting for horticultural therapy. At the same time, a total duration of 100-500 minutes provided better effects of stress reduction.

Discussion

We also developed a theoretical framework based on a "Participants-Settings-Interventions" structure for horticulture therapy in terms of its stress-reduction effects, to provide a reference for future horticultural therapy activities.

Psychophysiological Responses of Adults According to Cognitive Demand Levels for Horticultural Activities

We aimed to compare psychophysiological responses in adults according to cognitive demand levels for horticultural activities to confirm the feasibility of horticultural activity for improving attention and emotional states. A total of 60 adults in their 20s were included in this crossover design study. Participants performed soil-mixing activities with 2 cognitive demand levels for 2 min each. Electroencephalography (EEG) and electrocardiography (ECG) were performed during these activities. After each activity, the semantic differential method (SDM) was used to evaluate the emotional states of the participants. EEG results revealed that relative fast alpha and low beta power spectrums in the frontal lobes were high during the activity with high cognitive demand compared to those during the low demand activity, which indicates activation in the prefrontal cortex. ECG results showed that during the high cognitive demand activity, the standard deviation of the RR intervals of male adults was high, indicating a high-stress resistance ability of the autonomic nervous system. However, as a result of the SDM, there were no significant differences in emotional states according to the level of activity difficulty. Therefore, this study confirmed the possibility that the intervention of horticultural activities of an appropriate difficulty did not negatively affect subjective emotional changes and could have a positive effect on the improvement of attention levels and emotional stability in adults.