Physiological Effects of a Garden Plant Smellscape from the Perspective of Perceptual Interaction

Abstract

The purpose of this study was to investigate the physiological recovery effects of olfactory, visual and olfactory–visual stimuli associated with garden plants. In a randomized controlled study design, ninety-five Chinese university students were randomly selected to be exposed to stimulus materials, namely the odor of Osmanthus fragrans and a corresponding panoramic image of a landscape featuring the plant. Physiological indexes were measured by the VISHEEW multiparameter biofeedback instrument and a NeuroSky EEG tester in a virtual simulation laboratory. The results showed the following: (1) In the olfactory stimulation group, from before to during exposure to the stimuli, the subjects’ diastolic blood pressure (DBP) (ΔDBP = 4.37 ± 1.69 mmHg, p < 0.05) and pulse pressure (PP) values increased (ΔPP = −4.56 ± 1.24 mmHg, p < 0.05), while their pulse (p) values decreased (ΔP = −2.34 ± 1.16 bmp, p < 0.05) significantly. When compared to the control group, only the amplitudes of α and β brainwaves increased significantly (Δα = 0.37 ± 2.09 µV, Δβ = 0.34 ± 1.01 µV, p < 0.05). (2) In the visual stimulation group, the amplitudes of skin conductance (SC) (ΔSC = 0.19 ± 0.01 µΩ, p < 0.05), α brainwaves (Δα = 6.2 ± 2.26 µV, p < 0.05) and β brainwaves (Δβ = 5.51 ± 1.7 µV, p < 0.05) all increased significantly relative to the control group. (3) In the olfactory–visual stimulus group, DBP (ΔDBP = 3.26 ± 0.45 mmHg, p < 0.05) values increased, and PP values decreased (ΔPP = −3.48 ± 0.33 bmp, p < 0.05) significantly from before to during exposure to the stimuli. The amplitudes of SC (ΔSC = 0.45 ± 0.34 µΩ, p < 0.05), α brainwaves (Δα = 2.28 ± 1.74 µV, p < 0.05) and β brainwaves (Δβ = 1.4 ± 0.52 µV, p < 0.05) all increased significantly relative to the control group. The results of this study show that the interaction of olfactory and visual stimuli associated with a garden plant odor landscape was able to relax and refresh the body to a certain extent, and this physiological health effect was greater with regards to the integrated response of the autonomic nervous system and central nervous system than the effect of only smelling or viewing the stimuli. In the planning and designing of plant smellscapes in garden green space, it should be ensured that plant odors and corresponding landscapes are present at the same time in order to ensure the best health effect.

Development of A Relaxation Effect Evaluation System by Measuring Human Skin Comfort

“…Previous studies reported that the α-band increased due to aromatherapy [19], positive sound stimulation [20], listening to Mozart music [21], and audio-visual relaxation [22]. Another report indicated that olfactory-visual stimuli increased α-band and β-band [23]. Furthermore, it was reported that α power was correlated with resilience [24], and a correlation was observed between α peak frequency and calm score [25].…”

“…α is a frequency component of 8-13 Hz, which often appears mainly in the back of the head when the person is at rest with eyes closed and in a relaxed state. β is a frequency component of [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] Hz and a brain wave that often appears during an awake state. δ (delta) waves (0.5-< 4 Hz) and θ (theta) waves (4-< 8 Hz) have lower frequencies than alpha waves; therefore, they are considered slow waves and are noted during sleep.…”

Smellscape Characteristics of an Urban Park in Summer: A Case Study in Beijing, China

“…The effects of aromatic compounds on the brain in multi-sensory environmental interventions are thought to be directly mediated. Thus, smellscape is considered an important healing element in horticultural therapy, applied to comprehensive health outcomes including mental health, physical health, reduced agitation behavior, improved cognitive function, and improved well-being [30,31].…”