Physiological effects of visual stimulation with full-scale wall images composed of vertically and horizontally arranged wooden elements

Abstract

Wood is a raw material that is used not only in the production of structural members for various buildings, but also in the interior finishes that are directly seen and touched by the occupants. Wood has also been recognized as a humanfriendly material, but few studies have experimentally confirmed the physiological benefits it brings to humans. Therefore, the aim of the present study was to investigate the physiological effects of visual stimulation with wood. Two types of full-scale square, wooden-wall images composed of vertically or horizontally arranged lumber, were prepared using computer graphics and projected onto a large display to create the visual stimuli, and a gray image was also prepared as a control. Twenty-eight female Japanese university students participated in the study. The participants initially spent 60 s viewing the gray background (rest period) and then observed each of the wooden-wall images and the gray image separately in a random order for 90 s each. During the visual stimulation, the oxyhemoglobin (oxy-Hb) concentration as an indicator of prefrontal brain activity and heart rate variability as an indicator of autonomic nervous activity were continuously measured in each participant. Subjective evaluation of each visual stimulus was then performed using a modified semantic differential method and the Profile of Mood States 2nd Edition test. It was found that visual stimulation with either of the wooden interior wall images induced a significant decrease in oxy-Hb concentration in the left and right prefrontal cortex compared with the gray image. Furthermore, the subjective evaluation showed that the wooden-wall images provided a significantly more "comfortable, " "relaxed, " and "natural" impression than the gray image and decreased the negative mood states, with the vertically arranged wooden-wall image having a more positive effect than the horizontally arranged image.

Effects of visual exposure to wood on human affective states, physiological arousal and cognitive performance: A systematic review of randomized trials

“…Four experiments are characterized by short exposure times to wood (90 s) and low numbers of participants (between 14 and 28), 34,47–50 while the other five studies employed longer exposure times (10–75 min) and typically larger number of participants (between 12 and 119). 35,36,45,46,51,52 Five studies created wooden settings of only light colour wood, 35,36,45,47,48 two studies used only dark wood, 34,49,50 and two studies employed both light and dark wood, either separately in different settings or combined in the same room. 46,51,52 Five studies included solid wood, 35,48–52 three used wood composites 34,36,46 and one used images of wood.…”

The Mood-Improving Effect of Viewing Images of Nature and Its Neural Substrate

“…Its portable (in some models), less noisy, and less bodily constraining characteristics have made it the most common technique used by researchers to investigate the "online" brain activity during contact with nature. Employing fNIRS, previous studies have reported that viewing forest landscapes [16] or foliage plants [17]; viewing images of forests [18], garden landscapes [19], or a wooden interior wall [20,21]; smelling Japanese cypress leaf oil/air or Japanese cedar chips (for a review, [10]); touching a natural pothos leaf (Epipremnum aureum, [22]) or solid wood [23,24]; or transferring foliage plants [25] reduces the concentration of oxy-Hb in the prefrontal cortex (PFC). This has been interpreted as a calming or relaxing effect on the brain, which underlies many of the affective benefits or mood-improving effects achieved by contact with nature.…”

Physiological Effects of Visual Stimulation Using Knotty and Clear Wood Images among Young Women

“…Adult women in their 20 s were included with consideration of continuity with our previous research [18][19][20][21][22][23][24][25][26][27]31] on the effect of wood-derived stimuli on the physiological responses in humans. In addition, visual stimulation, study protocol, physiological measurements, psychological measurements, and statistical analysis in the study of Nakamura et al [31] were applied in the current investigation. Their research revealed the physiological effects via a vision when using images of a full-scale wall made up of horizontally and vertically arranged wooden elements on prefrontal cortex activity.…”

“…Thus, changes in the percentage of wood caused differential physiological changes, and visual stimulation in a room comprising 30% wood, a standard type of living room commercially available in Japan, induces a physiological relaxation effect. Recently, Nakamura et al [31] examined the effects of visual stimulation using two full-size square mural images arranged vertically and horizontally as well as knot-free clear wood on brain and autonomic nervous system activities among young women in their twenties. Results showed that visual stimulation using mural images arranged vertically and horizontally, compared with gray wall images, significantly decreased left and right prefrontal oxygenated hemoglobin concentrations.…”

“…Nakamura et al reported the research on the effect of wood-derived visual stimulation on prefrontal cortex activity [31]. Results indicated a significant reduction in the oxyhemoglobin level in bilateral prefrontal cortex activity of adult female university students by visual stimulation of horizontally and vertically displayed full-scale wall images composed of Japanese cedar wood for 90 s on a large display.…”