Comparison of Physiological and Psychological Relaxation Using Measurements of Heart Rate Variability, Prefrontal Cortex Activity, and Subjective Indexes after Completing Tasks with and without Foliage Plants

Abstract

Abstract:The objective of this study was to compare physiological and psychological relaxation by assessing heart rate variability (HRV), prefrontal cortex activity, and subjective indexes while subjects performed a task with and without foliage plants. In a crossover experimental design, 24 university students performed a task transferring pots with and without a foliage plant for 3 min. HRV and oxyhemoglobin (oxy-Hb) concentration in the prefrontal cortex were continuously measured. Immediately thereafter, subjective evaluation of emotions was performed using a modified semantic differential (SD) method and a profile of mood state questionnaire (POMS). Results showed that the natural logarithmic (ln) ratio of low frequency/high frequency, as an estimate of sympathetic nerve activity, was significantly lower while performing the task with foliage plants for the average 3 min measurement interval. Oxy-Hb concentration in the left prefrontal cortex showed a tendency to decrease in the 2-3 min interval in the task with foliage plants compared to the task without plants. Moreover, significant psychological relaxation according to POMS score and SD was demonstrated when the task involved foliage plants. In conclusion, the task involving foliage plants led to more physiological and psychological relaxation compared with the task without foliage plants.

Determining the Effects of a Horticultural Therapy Program for Improving the Upper Limb Function and Balance Ability of Stroke Patients

“…Previous studies have reported the effects of visual stimulation by green plants on physiological and psychological relaxation (Park et al, 2016d;Son et al, 1998). Specifically, Park et al (2017) reported that the reachinggrasping task with green plants showed a higher stabilizing effect on the autonomic nervous system such as cerebral blood flow and sympathetic nerve activity than the reaching-grasping task without a green plant. Therefore, performing functional tasks through horticultural activity can provide psychophysiological and psychological stabilization effects as well as the physical effects that are commonly obtained through the repetition of a functional task.…”

Foliage Plants Improve Concentration and Emotional Condition of Elementary School Students Performing an Intensive Assignment

“…Similar findings have been reported in previous studies. When 24 men in their 20s performed the same tasks with and without foliage plants, the oxyhemoglobin concentration in the left prefrontal cortex of the subjects was lowered when performing the task with plants; this result suggests that tasks involving living foliage plants induce more physiological relaxation than working without foliage plants (Park et al, 2017). Furthermore, they also felt significant positive emotions, such as being more comfortable, natural, and relaxed compared with performing the task without plants (Park et al, 2017).…”

“…When 24 men in their 20s performed the same tasks with and without foliage plants, the oxyhemoglobin concentration in the left prefrontal cortex of the subjects was lowered when performing the task with plants; this result suggests that tasks involving living foliage plants induce more physiological relaxation than working without foliage plants (Park et al, 2017). Furthermore, they also felt significant positive emotions, such as being more comfortable, natural, and relaxed compared with performing the task without plants (Park et al, 2017). According to Choi et al (2016), only a 5% index of indoor greenness could provide benefits in psychophysiological stability by stimulating the autonomic nervous system, such as EEG and heart rate variability, and is associated with positive feelings such as ''clean, '' ''soft,'' ''bright,'' ''warm,'' ''vibrant,'' ''comfortable,'' and ''fresh.…”

A Horticultural Therapy Program Focused on Succulent Cultivation for the Vocational Rehabilitation Training of Individuals with Intellectual Disabilities

“…Furthermore, working with plants has demonstrated psychophysiological effects, invoking positive emotional changes. For instance, participants who participated in activities using plants showed increased alpha-waves in the brain, stabilized brain blood flow, and heart beats [46,47]. In another study, 30 adults with intellectual disabilities who participated in horticultural activities exhibited steadiness of the autonomic nervous system and reductions in the stress hormone, cortisol [48].…”