Physiological and Psychological Benefits of Viewing an Autumn Foliage Mountain Landscape Image among Young Women

Abstract

Empirically, viewing nature landscapes, including mountains, can promote relaxation. This study aimed to examine the physiological and psychological effects of visual stimulation using an autumn foliage mountain landscape image on autonomic nervous and brain activities. We included 27 female university students who viewed mountain and city (control) landscape images displayed on a large, high-resolution display for 90 seconds. As an indicator of autonomic nervous activity, heart rate variability (high frequency [HF], reflecting parasympathetic nervous activity, and low frequency/high frequency [LF/HF], reflecting sympathetic nervous activity) and heart rate were recorded. Simultaneously, as an indicator of brain activity, oxyhemoglobin concentrations in the prefrontal cortex were assessed using near-infrared time-resolved spectroscopy. Viewing the mountain landscape image significantly increased HF, indicating increased parasympathetic nervous activity. Furthermore, the visual stimulation using the mountain image induced comfortable, relaxed, and natural feelings, as well as improved mood states. In conclusion, viewing an autumn foliage mountain landscape image via large display induced physiological and psychological relaxation in women in their 20s.

Full text

Citation: Jo, H.; Ikei, H.; Miyazaki, Y.
Physiological and Psychological
Benefits of Viewing an Autumn
Foliage Mountain Landscape Image
among Young Women. Forests 2022,
13, 1492. https://doi.org/10.3390/
f13091492
Academic Editor: Luis Diaz-Balteiro
Received: 4 August 2022
Accepted: 9 September 2022
Published: 15 September 2022
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Article
Physiological and Psychological Benefits of Viewing an Autumn
Foliage Mountain Landscape Image among Young Women
Hyunju Jo †, Harumi Ikei †and Yoshifumi Miyazaki *
Center for Environment, Health and Field Sciences, Chiba University, Kashiwa 277-0882, Japan
*Correspondence: ymiyazaki@faculty.chiba-u.jp
† These authors contributed equally to this work.
Abstract:
Empirically, viewing nature landscapes, including mountains, can promote relaxation.
This study aimed to examine the physiological and psychological effects of visual stimulation using
an autumn foliage mountain landscape image on autonomic nervous and brain activities. We
included 27 female university students who viewed mountain and city (control) landscape images
displayed on a large, high-resolution display for 90 seconds. As an indicator of autonomic nervous
activity, heart rate variability (high frequency [HF], reflecting parasympathetic nervous activity, and
low frequency/high frequency [LF/HF], reflecting sympathetic nervous activity) and heart rate
were recorded. Simultaneously, as an indicator of brain activity, oxyhemoglobin concentrations in
the prefrontal cortex were assessed using near-infrared time-resolved spectroscopy. Viewing the
mountain landscape image significantly increased HF, indicating increased parasympathetic nervous
activity. Furthermore, the visual stimulation using the mountain image induced comfortable, relaxed,
and natural feelings, as well as improved mood states. In conclusion, viewing an autumn foliage
mountain landscape image via large display induced physiological and psychological relaxation in
women in their 20s.
Keywords: autumn mountain; heart rate variability; natural landscape image; nature therapy; near-
infrared spectroscopy; physiological and psychological relaxation; stress reduction
1. Introduction
From 6–7 million years ago, humans underwent evolution until they reached their
current form [
1
]. The evolution took place in a natural environment more than 99.99%
of the time. However, today, it is considered that we are under a stress state because we
inhabit an urbanized and artificial environment [2,3].
In recent decades, the stress recovery and relaxation effects of nature have attracted
attention worldwide [
4
,
5
]. The scientific data on the physiological effects of nature have
been accumulated [
2
,
6
]. Previous studies performed field experiments in forests [
7
–
10
] and
parks [
11
,
12
], and indoor experiments have focused on the sensory effects of various senses,
such as visual [13,14], olfactory [15,16], tactile [17,18], and auditory [19,20].
Various nature-derived stimuli have been used to study the visual effects in indoor
experiments [
21
]. The studies have reported the physiological relaxing effects on the brain
and autonomic nervous system activity by viewing natural landscapes through display [
22
]
and slide [
23
] and by viewing other actual natural stimuli, including flowers [
24
,
25
], foliage
plants [26,27], and bonsai trees [28,29].
To validate the physiological and psychological relaxing effects of a natural landscape
by indoor experiment, it is important to present a stimulus with a realistic sensation, such as
being in a field. Recently, virtual reality [
30
] and large, high-resolution displays [
22
] have
been utilized as stimulation methods to enhance realism. Song et al. [
22
] investigated the
physiological and psychological effects of a green Metasequoia forest landscape image on a
large, high-resolution display, which was the same as the one used in the current experiment.
Forests 2022,13, 1492. https://doi.org/10.3390/f13091492 https://www.mdpi.com/journal/forests

Forests 2022,13, 1492 2 of 10
The results showed that compared with the city image, the green forest image induced a
physiological relaxing effect that significantly decreased oxyhemoglobin concentrations in
the right prefrontal cortex. Furthermore, the forest image resulted in a psychological effect
inducing slightly comfortable, slightly relaxed, and moderately natural feelings.
On the other hand, although autumn foliage has a special meaning for the Japanese
people, scientific data have not yet been reported regarding the physiological relaxing
effects of natural landscapes with autumn foliage. In Japan, there is a tradition called
“momijigari”, which is to visit scenic areas where leaves have turned red in the autumn [
31
],
and several tourist destinations hold “momijigari” in autumn [
32
]. Liu et al. [
33
] have
reported a correlation between the number of tourists and the time of autumn foliage, indi-
cating that autumn foliage is a special natural landscape for Japanese people. Although no
previous studies have reported on the effects of viewing autumn foliage landscapes, some
studies have reported that viewing colored flowers, such as red [
24
] and pink roses [
13
],
induced visual physiological relaxation. In addition, some field experiments focused on
natural seasonality; Song et al. found that walking in an urban park in spring [
12
], fall [
34
],
and winter [11] induced physiological relaxation.
Therefore, the present study aimed to verify the physiological and psychological
effects of a realistic autumn mountain landscape image with autumn foliage on a large,
high-resolution display compared with a city image. To evaluate physiological responses,
we measured sympathetic and parasympathetic nervous activities in terms of heart rate
variability (HRV) and heart rate and prefrontal cortex activity in terms of oxyhemoglobin
(oxy-Hb) concentrations in the left and right prefrontal cortices using near-infrared time-
resolved spectroscopy (TRS), which allows absolute value measurements. To evaluate
psychological responses, we used the modified semantic differential (SD) method and the
Profile of Mood States second edition (POMS 2).
2. Materials and Methods
Experimental procedures and physiological and psychological measurements were
performed, as described by Song et al. [22]. The short version of the POMS 2 was used, as
stated by Ikei et al. [18].
2.1. Participants
A total of 27 female Japanese university students were recruited (mean
±
standard
deviation: age, 23.2
±
2.4 years; weight, 48.0
±
4.4 kg; height, 155.7
±
4.4 cm; right and left
eyesight, 0.9
±
0.3 and 0.9
±
0.3, respectively [based on the decimal vision acuity system
used in Japan]). The exclusion criteria were participants with respiratory illness, poor
physical condition, and <0.3 eyesight (including the corrected value) in the right and left
eyes. Furthermore, we excluded females who were menstruating during the experiment
period, because it is known that women during the menstrual period experience debilitating
menstrual symptoms [
35
], such as mental fatigue [
36
]. The applicability of these criteria
was self-reported.
The study was approved by the Ethics Committee of the Center for Environment,
Health, and Field Sciences at Chiba University, Japan (project ID no. 42), and the research
information was registered in the University Hospital Medical Information Network of
Japan (ID no. UMIN000039320). We used a randomized block design to assign participants
to one of two intervention groups in a different order of viewing images (Figure 1).

Forests 2022,13, 1492 3 of 10
Forests 2022, 13, x FOR PEER REVIEW 3 of 11
Figure 1. Flowchart of the experiment based on the CONSORT statement. Participant screening,
enrollment, follow-up, and analysis flow. HRV (heart rate variability), TRS (near-infrared time-re-
solved spectroscopy).
2.2. Visual Exposure
Figure 2 shows the image used during visual exposure. The mountain image (Figure
2A) used herein was that of the Mount Bandai landscape in Fukushima Prefecture during
the autumn foliage season. Mount Bandai is one of the most famous mountains in Japan,
especially for autumn foliage. The city image (Figure 2B, control) was that of the sky-
scraper landscape of Shinjuku, a typical building district in the capital city of Tokyo. Each
image was displayed on a high-resolution large plasma display (1872 [W] × 1053 [H] mm;
3840 × 2160 pixel resolution; 85 V type, TH-85AX900 by Panasonic, Osaka, Japan). Based
on the preliminary test, the distance between the participants and the display that would
fully facilitate visual stimulation but not cause discomfort was set to 1.1 m.
Figure 2. Images used in visual exposure. (A) Mountain image: Mount Bandai autumn landscape,
Fukushima. (B) City image: Skyscraper landscape in Shinjuku, Tokyo.
Figure 1.
Flowchart of the experiment based on the CONSORT statement. Participant screening,
enrollment, follow-up, and analysis flow. HRV (heart rate variability), TRS (near-infrared time-
resolved spectroscopy).
2.2. Visual Exposure
Figure 2shows the image used during visual exposure. The mountain image (
Figure 2A
)
used herein was that of the Mount Bandai landscape in Fukushima Prefecture during the au-
tumn foliage season. Mount Bandai is one of the most famous mountains in Japan, especially
for autumn foliage. The city image (Figure 2B, control) was that of the skyscraper landscape
of Shinjuku, a typical building district in the capital city of Tokyo. Each image was displayed
on a high-resolution large plasma display (1872 [W]
×
1053 [H] mm;
3840 ×2160
pixel
resolution; 85 V type, TH-85AX900 by Panasonic, Osaka, Japan). Based on the preliminary
test, the distance between the participants and the display that would fully facilitate visual
stimulation but not cause discomfort was set to 1.1 m.
Forests 2022, 13, x FOR PEER REVIEW 3 of 11
Figure 1. Flowchart of the experiment based on the CONSORT statement. Participant screening,
enrollment, follow-up, and analysis flow. HRV (heart rate variability), TRS (near-infrared time-re-
solved spectroscopy).
2.2. Visual Exposure
Figure 2 shows the image used during visual exposure. The mountain image (Figure
2A) used herein was that of the Mount Bandai landscape in Fukushima Prefecture during
the autumn foliage season. Mount Bandai is one of the most famous mountains in Japan,
especially for autumn foliage. The city image (Figure 2B, control) was that of the sky-
scraper landscape of Shinjuku, a typical building district in the capital city of Tokyo. Each
image was displayed on a high-resolution large plasma display (1872 [W] × 1053 [H] mm;
3840 × 2160 pixel resolution; 85 V type, TH-85AX900 by Panasonic, Osaka, Japan). Based
on the preliminary test, the distance between the participants and the display that would
fully facilitate visual stimulation but not cause discomfort was set to 1.1 m.
Figure 2. Images used in visual exposure. (A) Mountain image: Mount Bandai autumn landscape,
Fukushima. (B) City image: Skyscraper landscape in Shinjuku, Tokyo.
Figure 2.
Images used in visual exposure. (
A
) Mountain image: Mount Bandai autumn landscape,
Fukushima. (B) City image: Skyscraper landscape in Shinjuku, Tokyo.
2.3. Study Protocol
Figure 3depicts the measurement protocol. The participants were fitted with the
physiological measurement sensors and were instructed to rest in an artificial climate
chamber (temperature, 24
◦
C; relative humidity, 50%) while viewing a gray image (rest

Forests 2022,13, 1492 4 of 10
period: 60 s). Next, they were exposed to either the mountain or city image (stimulation
period: 90 s). After the physiological measurement, the questionnaires for the subjective
test were answered (120 s). This study used a within-participant design, and the mountain
or city image was presented in a counterbalanced order.
Forests 2022, 13, x FOR PEER REVIEW 4 of 11
2.3. Study Protocol
Figure 3 depicts the measurement protocol. The participants were fitted with the
physiological measurement sensors and were instructed to rest in an artificial climate
chamber (temperature, 24 °C; relative humidity, 50%) while viewing a gray image (rest
period: 60 s). Next, they were exposed to either the mountain or city image (stimulation
period: 90 s). After the physiological measurement, the questionnaires for the subjective
test were answered (120 s). This study used a within-participant design, and the mountain
or city image was presented in a counterbalanced order.
Figure 3. Measurement protocol for visual stimulation with mountain and city landscape images.
The orders of mountain and city images were counterbalanced. The study employed a within-par-
ticipant design.
2.4. Physiological Measurements
Figure 4 shows the method of assessment of physiological indicators. To evaluate
autonomic nervous activity, we used HRV and heart rate with a portable electrocardio-
graph (Activtracer AC-301A; GMS, Tokyo, Japan) [37,38]. HRV was analyzed for the pe-
riods between consecutive R waves (R-R intervals, RRI). High frequency (HF; 0.15–0.40 Hz)
and low frequency (LF; 0.04–0.15 Hz) power level components were calculated using the
maximum entropy method (Mem-Calc/Win; GMS, Tokyo, Japan) [39,40]. The HF power
indicated parasympathetic nervous activity, and the LF/HF power ratio indicated sympa-
thetic nervous activity [37,41]. To evaluate brain activity, we used TRS (TRS-20 system;
Hamamatsu Photonics K.K., Shizuoka, Japan) [42,43]. We measured oxy-Hb concentra-
tions in the prefrontal cortex. Changes in oxy-Hb concentrations are known to be con-
sistent with the changes in blood flow in the brain, and it is thought that a decrease in oxy-
Hb concentration is associated with physiological calming [44]. It has been reported that
oxy-Hb concentrations in the prefrontal cortex are reduced by pleasant emotions and in-
creased by unpleasant emotions [45]. The value of physiological responses during visual
stimulation (90 s) was calculated as the differences from the mean value for 30 s before
exposure.
Figure 4. Assessment of physiological indicators.
Figure 3.
Measurement protocol for visual stimulation with mountain and city landscape images.
The orders of mountain and city images were counterbalanced. The study employed a within-
participant design.
2.4. Physiological Measurements
Figure 4shows the method of assessment of physiological indicators. To evaluate
autonomic nervous activity, we used HRV and heart rate with a portable electrocardiograph
(Activtracer AC-301A; GMS, Tokyo, Japan) [
37
,
38
]. HRV was analyzed for the periods
between consecutive R waves (R-R intervals, RRI). High frequency (HF; 0.15–0.40 Hz)
and low frequency (LF; 0.04–0.15 Hz) power level components were calculated using the
maximum entropy method (Mem-Calc/Win; GMS, Tokyo, Japan) [
39
,
40
]. The HF power
indicated parasympathetic nervous activity, and the LF/HF power ratio indicated sym-
pathetic nervous activity [
37
,
41
]. To evaluate brain activity, we used TRS (TRS-20 system;
Hamamatsu Photonics K.K., Shizuoka, Japan) [
42
,
43
]. We measured oxy-Hb concentrations
in the prefrontal cortex. Changes in oxy-Hb concentrations are known to be consistent
with the changes in blood flow in the brain, and it is thought that a decrease in oxy-Hb
concentration is associated with physiological calming [
44
]. It has been reported that oxy-Hb
concentrations in the prefrontal cortex are reduced by pleasant emotions and increased by
unpleasant emotions [
45
]. The value of physiological responses during visual stimulation
(90 s) was calculated as the differences from the mean value for 30 s before exposure.
Forests 2022, 13, x FOR PEER REVIEW 4 of 11
2.3. Study Protocol
Figure 3 depicts the measurement protocol. The participants were fitted with the
physiological measurement sensors and were instructed to rest in an artificial climate
chamber (temperature, 24 °C; relative humidity, 50%) while viewing a gray image (rest
period: 60 s). Next, they were exposed to either the mountain or city image (stimulation
period: 90 s). After the physiological measurement, the questionnaires for the subjective
test were answered (120 s). This study used a within-participant design, and the mountain
or city image was presented in a counterbalanced order.
Figure 3. Measurement protocol for visual stimulation with mountain and city landscape images.
The orders of mountain and city images were counterbalanced. The study employed a within-par-
ticipant design.
2.4. Physiological Measurements
Figure 4 shows the method of assessment of physiological indicators. To evaluate
autonomic nervous activity, we used HRV and heart rate with a portable electrocardio-
graph (Activtracer AC-301A; GMS, Tokyo, Japan) [37,38]. HRV was analyzed for the pe-
riods between consecutive R waves (R-R intervals, RRI). High frequency (HF; 0.15–0.40 Hz)
and low frequency (LF; 0.04–0.15 Hz) power level components were calculated using the
maximum entropy method (Mem-Calc/Win; GMS, Tokyo, Japan) [39,40]. The HF power
indicated parasympathetic nervous activity, and the LF/HF power ratio indicated sympa-
thetic nervous activity [37,41]. To evaluate brain activity, we used TRS (TRS-20 system;
Hamamatsu Photonics K.K., Shizuoka, Japan) [42,43]. We measured oxy-Hb concentra-
tions in the prefrontal cortex. Changes in oxy-Hb concentrations are known to be con-
sistent with the changes in blood flow in the brain, and it is thought that a decrease in oxy-
Hb concentration is associated with physiological calming [44]. It has been reported that
oxy-Hb concentrations in the prefrontal cortex are reduced by pleasant emotions and in-
creased by unpleasant emotions [45]. The value of physiological responses during visual
stimulation (90 s) was calculated as the differences from the mean value for 30 s before
exposure.
Figure 4. Assessment of physiological indicators.
Figure 4. Assessment of physiological indicators.
2.5. Psychological Measurements
The psychological effects of visual stimuli were assessed using the modified SD
method [
46
] and POMS 2 [
47
,
48
]. The modified SD method consisted of three paired
adjectives (comfortable
−
uncomfortable, relaxed
−
awakening, and natural
−
artificial) to
assess impressions of the stimuli. POMS 2 of seven subscales (A–H, anger–hostility; C–B,
confusion–bewilderment; D–D, depression–dejection; F–I, fatigue–inertia; T–A, tension–

Forests 2022,13, 1492 5 of 10
anxiety; V–A, vigor–activity; and F, friendliness) and total mood disturbance (TMD) were
used to assess changes in mood states to the stimuli. To reduce participant burden, a
shortened Japanese version of the POMS 2 with 35 questions was used.
2.6. Data Analysis
The Statistical Package for the Social Sciences software (version 21.0, IBM, Armonk,
NY, USA) was used for statistical analysis. p< 0.05 was considered statistically significant.
Paired t-tests were used to compare the physiological responses (HRV, heart rate, TRS,
and respiratory rate) between mountain and city images based on the overall mean value
during 90-s visual exposures. The Wilcoxon signed-rank test was applied to compare the
psychological effects (the modified SD method and POMS 2) of the mountain and city images.
3. Results
3.1. Physiological Effects
3.1.1. HRV and Heart Rate
We excluded one participant who showed a large change in respiratory rate while
viewing the images because variations in these values could influence HRV data. No
significant differences were noted in the respiratory rate between participants who viewed
a mountain image and those who viewed a city image. Therefore, a statistical analysis of
the HRV data was performed.
Figure 5shows the results of the HF component, indicating parasympathetic nervous
activity by exposure to mountain and city images. Figure 5A depicts the changes in 30-s
mean HF component over 90-s exposure. During exposure to the mountain image, the HF
component increased to 243.46
±
113.52 ms
2
between 31 and 60 s and
198.95 ±104.45 ms2
between 61 and 90 s; however, during exposure to the city image, the HF component
almost stayed at the baseline. Figure 5B displays the changes in the HF component during
exposure to the mountain and city images for 90 s. In comparing the overall means in
the 90-s exposure period, the HF component value of the participants who viewed the
mountain image was significantly higher than that of the participants who viewed the city
image (Figure 5B, mountain: 171.91 ±78.98 ms2; city: 31.18 ±77.35 ms2;p= 0.037).
Forests 2022, 13, x FOR PEER REVIEW 6 of 11
Figure 5. Changes in the high frequency (HF) of heart rate variability (HRV) for exposure to the
mountain and city images. (A) Changes in the 30-s mean HF component over 90 s of exposure
(difference from the mean value for 30 s before exposure). (B) Changes in HF during exposure to
the mountain and city images for 90 s. (n = 26, mean ± standard error). * p < 0.05 (mountain vs. city),
paired t-test.
3.1.2. TRS
No significant differences were noted in ⊿oxyhemoglobin concentrations on the left
(mountain: −0.37 ± 0.17 µM; city: −0.41 ± 0.25 µM; p = 0.910) and right (mountain: −0.45 ±
0.18 µM; city: −0.25 ± 0.14 µM; p = 0.324) prefrontal cortices between the participants who
viewed the mountain image and those who viewed the city image.
3.2. Psychological Effects
Figure 6 shows the psychological responses of the participants, as measured using
the modified SD method, after viewing the mountain and city images. In the
comfortable−uncomfortable subscale, visual stimulation using the mountain image
promoted slight to moderate comfort, and visual stimulation using the city image induced
almost indifferent feelings. Thus, visual stimulation using the mountain image provided
a more comfortable feeling than visual stimulation using the city image (Figure 6A, p <
0.001). In the relaxed−awakening subscale, visual stimulation using the mountain image
induced slight to moderate relaxation, and visual stimulation using the city promoted
slight awakening. Therefore, visual stimulation using the mountain image induced a more
relaxed feeling than visual stimulation using the city image (Figure 6B, p < 0.001).
Additionally, in the natural−artificial subscale, visual stimulation using the mountain
image promoted moderate to very natural feelings, and visual stimulation using the city
image induced almost moderate artificial feelings. Thus, the mountain image promoted a
more natural feeling than the city image (Figure 6C, p < 0.001).
Figure 5.
Changes in the high frequency (HF) of heart rate variability (HRV) for exposure to the
mountain and city images. (
A
) Changes in the 30-s mean HF component over 90 s of exposure
(difference from the mean value for 30 s before exposure). (
B
) Changes in HF during exposure to the
mountain and city images for 90 s. (n= 26, mean
±
standard error). * p< 0.05 (mountain vs. city),
paired t-test.
However, no significant differences were observed in the
∆
LF/HF value, indicating the
sympathetic nervous activity (mountain:
−
0.23
±
0.39; city: 0.31
±
0.28; p= 0.340) and
∆
heart
rate (mountain:
−
0.64
±
0.50 beats/min; city:
−
0.05
±
0.34 beats/min; p= 0.234) between the
participants who viewed the mountain image and those who viewed the city image.

Forests 2022,13, 1492 6 of 10
3.1.2. TRS
No significant differences were noted in
∆
oxyhemoglobin concentrations on the left
(mountain:
−
0.37
±
0.17
µ
M; city:
−
0.41
±
0.25
µ
M; p= 0.910) and right (mountain:
−0.45 ±0.18 µM
; city:
−
0.25
±
0.14
µ
M; p= 0.324) prefrontal cortices between the partici-
pants who viewed the mountain image and those who viewed the city image.
3.2. Psychological Effects
Figure 6shows the psychological responses of the participants, as measured using the
modified SD method, after viewing the mountain and city images. In the comfortable
−
uncomfortable subscale, visual stimulation using the mountain image promoted slight to
moderate comfort, and visual stimulation using the city image induced almost indifferent feel-
ings. Thus, visual stimulation using the mountain image provided a more comfortable feeling
than visual stimulation using the city image (Figure 6A, p< 0.001). In the relaxed
−
awakening
subscale, visual stimulation using the mountain image induced slight to moderate relaxation,
and visual stimulation using the city promoted slight awakening. Therefore, visual stim-
ulation using the mountain image induced a more relaxed feeling than visual stimulation
using the city image (Figure 6B, p< 0.001). Additionally, in the natural
−
artificial subscale,
visual stimulation using the mountain image promoted moderate to very natural feelings, and
visual stimulation using the city image induced almost moderate artificial feelings. Thus, the
mountain image promoted a more natural feeling than the city image (Figure 6C, p< 0.001).
Forests 2022, 13, x FOR PEER REVIEW 7 of 11
Figure 6. Psychological effects evaluated using the modified SD method based on three opposing
adjective pairs after viewing the mountain and city images. (A) Comfortable versus uncomfortable.
(B) Relaxed versus awakening. (C) Natural versus artificial (n = 27, mean ± standard error). ** p <
0.01 (mountain vs. city). Wilcoxon signed-rank test.
Figure 7 shows the results of the seven subscales and the TMD scores based on the
POMS 2 questionnaires after visual stimulation using the mountain and city images. The
participants who viewed the mountain image had significantly lower negative subscale
scores than those who viewed the city image (A–H, anger–hostility [p < 0.01]; C–B,
confusion–bewilderment [p < 0.001]; F–I, fatigue–inertia [p < 0.001]; T–A, tension–anxiety
[p < 0.001]), except for the subscale of D–D, depression–dejection (p > 0.05). However, they
had significantly higher positive subscale scores (V–A, vigor–activity [p < 0.001]; F,
friendliness [p < 0.01]). Further, participants who viewed the mountain image had
significantly lower TMD scores than those who viewed the city image (p < 0.001).
Figure 7. Psychological effects evaluated by POMS 2 after viewing the mountain and city images.
(n = 27, mean ± standard error, ** p < 0.01 [mountain vs. city], Wilcoxon signed-rank test). A–H,
anger–hostility; C–B, confusion–bewilderment; D–D, depression–dejection; F–I, fatigue–inertia; T–
A, tension–anxiety; V–A, vigor–activity; F, friendliness; TMD, total mood disturbance.
4. Discussion
The present study demonstrated that visual stimulation using an autumn foliage
mountain landscape image via a large display can induce physiological and psychological
relaxation effects among women in their 20s.
Figure 6.
Psychological effects evaluated using the modified SD method based on three opposing
adjective pairs after viewing the mountain and city images. (
A
) Comfortable versus uncomfortable.
(
B
) Relaxed versus awakening. (
C
) Natural versus artificial (n= 27, mean
±
standard error).
** p< 0.01
(mountain vs. city). Wilcoxon signed-rank test.
Figure 7shows the results of the seven subscales and the TMD scores based on
the POMS 2 questionnaires after visual stimulation using the mountain and city images.
The participants who viewed the mountain image had significantly lower negative sub-
scale scores than those who viewed the city image (A–H, anger–hostility [p< 0.01]; C–B,
confusion–bewilderment [p< 0.001]; F–I, fatigue–inertia [p< 0.001]; T–A, tension–anxiety
[
p< 0.001
]), except for the subscale of D–D, depression–dejection (p> 0.05). However, they
had significantly higher positive subscale scores (V–A, vigor–activity [
p< 0.001
]; F, friendli-
ness [p< 0.01]). Further, participants who viewed the mountain image had significantly
lower TMD scores than those who viewed the city image (p< 0.001).

Forests 2022,13, 1492 7 of 10
Forests 2022, 13, x FOR PEER REVIEW 7 of 11
Figure 6. Psychological effects evaluated using the modified SD method based on three opposing
adjective pairs after viewing the mountain and city images. (A) Comfortable versus uncomfortable.
(B) Relaxed versus awakening. (C) Natural versus artificial (n = 27, mean ± standard error). ** p <
0.01 (mountain vs. city). Wilcoxon signed-rank test.
Figure 7 shows the results of the seven subscales and the TMD scores based on the
POMS 2 questionnaires after visual stimulation using the mountain and city images. The
participants who viewed the mountain image had significantly lower negative subscale
scores than those who viewed the city image (A–H, anger–hostility [p < 0.01]; C–B,
confusion–bewilderment [p < 0.001]; F–I, fatigue–inertia [p < 0.001]; T–A, tension–anxiety
[p < 0.001]), except for the subscale of D–D, depression–dejection (p > 0.05). However, they
had significantly higher positive subscale scores (V–A, vigor–activity [p < 0.001]; F,
friendliness [p < 0.01]). Further, participants who viewed the mountain image had
significantly lower TMD scores than those who viewed the city image (p < 0.001).
Figure 7. Psychological effects evaluated by POMS 2 after viewing the mountain and city images.
(n = 27, mean ± standard error, ** p < 0.01 [mountain vs. city], Wilcoxon signed-rank test). A–H,
anger–hostility; C–B, confusion–bewilderment; D–D, depression–dejection; F–I, fatigue–inertia; T–
A, tension–anxiety; V–A, vigor–activity; F, friendliness; TMD, total mood disturbance.
4. Discussion
The present study demonstrated that visual stimulation using an autumn foliage
mountain landscape image via a large display can induce physiological and psychological
relaxation effects among women in their 20s.
Figure 7.
Psychological effects evaluated by POMS 2 after viewing the mountain and city images.
(n= 27, mean
±
standard error, ** p< 0.01 [mountain vs. city], Wilcoxon signed-rank test). A–H,
anger–hostility; C–B, confusion–bewilderment; D–D, depression–dejection; F–I, fatigue–inertia; T–A,
tension–anxiety; V–A, vigor–activity; F, friendliness; TMD, total mood disturbance.
4. Discussion
The present study demonstrated that visual stimulation using an autumn foliage
mountain landscape image via a large display can induce physiological and psychological
relaxation effects among women in their 20s.
Results of physiological effects showed that the autonomic nervous activity, viewing
an image of a mountain, significantly increased the parasympathetic nervous activity of
the HF component compared with viewing a city image. The modified SD method and
POMS 2 showed that the psychological effects of viewing the mountain image induced
comfortable, relaxed, and natural feelings, as well as improved mood states.
Ikei et al. have demonstrated the following: (1) visual stimulation of fresh roses in a
vase increased the parasympathetic nervous activity in office workers [
13
] and (2) visual
stimulation of Dracaena foliage plants also increased the parasympathetic nervous activity
in high school students [
27
]. Studies using a bonsai tree as a visual stimulus demonstrated
that older adult patients undergoing rehabilitation [
28
] and patients with spinal cord
injury [
29
] who were under highly stressed conditions increased their parasympathetic
nervous activity by observing the bonsai tree for 1 min. Gladwell et al. [23] have reported
that viewing slides of natural scenery, such as trees and grass fields, significantly increased
parasympathetic nervous activity. Similar to the results of the previous studies, the results
of the present study confirmed that exposure to an autumn mountain landscape image via
a large, high-resolution display increased parasympathetic activity. These results suggest
that visual exposure to indoor plants, such as flowers, ornamental foliage, and bonsai
tree, or to the natural landscape via slides or displays results in physiological relaxation
and stress reduction. On the other hand, previous studies on visual effects showed that
visual stimuli induced changes in both the autonomic nervous system (sympathetic or/and
parasympathetic nervous activity) and prefrontal cortex [
29
,
49
]. However, in the current
study, only parasympathetic activity increased as a result of the visual stimulation of the
mountain image. The reason for this is unknown, and further investigations are needed to
acquire more data.
The psychological assessment finding in the current study showed that exposure to
the mountain image elicited greater comfortable, relaxed, and natural feelings, as well as
improved mood states, than exposure to the city image. This is a psychological effect that
is also consistent with staring at a rose for 3 min [
13
,
24
] and a bonsai tree with a reduced
forest landscape for 1 min [
29
]. This indicates that indirect viewing of nature landscape
images through displays and brief visual exposure to indoor plants, such as flowers and
bonsai trees, can lead to psychological relaxation.

Forests 2022,13, 1492 8 of 10
Since 2019, due to the COVID-19 pandemic, people are spending more time in their
homes owing to telework, school closures, and their own choices to self-isolate. Moreover,
several are experiencing stress owing to significant changes in lifestyle patterns [
50
,
51
]. The
current study showed that an indirect observation of a large display of nature landscape
images for a short time induces physiological and psychological relaxation. Indirect ex-
posure to nature landscape images projected on a display could alleviate stress caused by
these new social situations.
However, the current study had several limitations. (1) Future studies are needed to
validate the physiological and psychological effects of visual stimulation using a home
personal computer or a general TV screen, which are commonly used. (2) This study
focused on the effects of landscape images consisting of mountains and buildings, which
are typical examples of nature and city landscapes, respectively. In the future, research on
different landscape types, such as a magnificent waterfall, is expected to elicit different
responses that expand the range of physiological and psychological responses recorded for
these categories of visual stimuli. (3) Factors such as the color, line, shape, and texture of
the stimuli affect visual perception. In the future, it is necessary to consider such factors as
evaluation scales in the modified SD method. (4) This study was limited to a short exposure
time of 90 s and to the effects of visual stimuli. Further studies on the effects of long-term
exposure to visual stimuli as well as the effects of stimulating auditory, tactile, olfactory,
and other senses will further deepen the knowledge in this field. (5) The study participants
were limited to women in their 20s. Future studies with a larger number of participants of
different ages and gender need to be conducted for the generalizability of the results.
5. Conclusions
The current study demonstrated the physiological and psychological effects of viewing
an autumn foliage mountain landscape image via a large, high-resolution display. The au-
tonomic nervous activity and the prefrontal cortex activity were simultaneously measured.
Results revealed that visual stimulation with the mountain image significantly increased
parasympathetic nervous activity and promoted comfortable, relaxed, and natural feelings,
as well as improved mood states. In conclusion, visual stimulation using an autumn foliage
mountain landscape image via a large display induced physiological and psychological
relaxation among women in their 20s.
Author Contributions:
Conceptualization, H.I. and Y.M.; methodology, H.I. and Y.M.; investigation,
H.J., H.I. and Y.M.; resources, H.I. and Y.M.; data curation, H.J. and H.I.; writing—original draft
preparation, H.J.; writing—review and editing, H.J., H.I. and Y.M.; visualization, H.J. and H.I.;
supervision, Y.M.; project administration, H.I. and Y.M.; funding acquisition, H.I. and Y.M. All
authors have read and agreed to the published version of the manuscript.
Funding: This research was funded by Ookawaso.
Institutional Review Board Statement:
Informed consent was obtained from all subjects involved
in the study. The study was conducted according to the guidelines of the Declaration of Helsinki,
and approved by the Ethics Committee of the Center for Environment, Health, and Field Sciences at
Chiba University, Japan (project ID no. 42, approval date 20 January 2020).
Data Availability Statement:
The data that support the finding of this study are available from the
corresponding author upon reasonable request.
Acknowledgments:
We would like to appreciate Hiromitsu Kobayashi of the Ishikawa Prefecture
Nursing University for his contribution to analyzing the HRV signals to estimate the respiratory rate.
This paper is an achievement of the research project of “elucidation of the physiological relaxing
effects of the visual stimulation of a waterfall and a forest” commissioned from Ookawaso.
Conflicts of Interest: The authors declare no conflict of interest.

Forests 2022,13, 1492 9 of 10
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