It is known that the colors in our surroundings affect emotions. In our previous study, we set up an environment in which a specific emotional state was triggered by conversation and investigated the lighting conditions that promote the emotional state through psychophysical experiments. We found no significant effect on positive emotional states, such as happiness, under a single uniform lighting condition generated by a recall color. In contrast, negative emotional states, such as sadness, were significantly promoted under a single uniform lighting condition. In this study, we investigate the lighting conditions that promote positive emotions through psychophysical experiments. The results of the experiment showed that happiness, as a positive emotional state, could be steadily promoted by illumination with a spatial combination of a color recalled from the emotion and its opponent color.
Since Goethe intuitively stated that color categories (e.g., yellow and red-yellow)
are associated with emotional responses (e.g., warmth and excitement), theories of
color and psychological functioning have advanced in the fields of evolutionary
psychology, emotion science, and person perception [
In recent years, a variety of empirical studies have surfaced in the field of indoor
design, providing evidence that the color of an indoor space can affect the psychological
emotions of the people in that space. Many studies have compared the effects of “warm”
colors and “cool” colors (for e.g. red and blue, respectively) [
Most of these studies focus on finding the input-output relationship between color
stimuli and their effects in a neutral state. However, emotions change dynamically in
the real world. Therefore, it is essential to consider emotional states in the analyses
performed for practical applications. In our previous study [
In this study, we experimentally investigate the lighting conditions that promote positive emotions in a room. 2
In our previous study [
The negative emotional states “noisy” and “sad” were at the maximum absolute
value for lighting color 1. In contrast, in the positive emotional state “happy,” the factor
score in the neutral state was high, and lighting color 1 did not promote emotion. The
experimental results in our previous study [
In this section, we describe an experiment where spatially illuminate multiple colors to
promote the “happy” emotional state. In this study, we base one of the multiple color
schemes on physiological findings [
Figure 2 shows the experimental room. The purpose of this experiment is not to investigate visual mechanisms such as color adaptation, but rather the effects of lighting colors on emotions. Considering that the real environment, including lighting, is reflected sensitively in emotions, we constructed a small room in which natural conversations could be held instead of using a laboratory environment such as a darkroom. The room was 1.642 m long and 2.552 m wide, and a few people could be seated at a table for discussions. The colors of the interiors, wallpaper, floor tiles, and curtains were achromatic to avoid chromatic effects on the ambient light.
On the ceiling, nine LED lights (Philips Hue) were installed. The irradiation angle was variable, and the dimming and toning could be controlled spatially and temporally by a program. Figure 3 shows the measurement results for the color gamut of illumination. The LEDs cover the Adobe RGB color gamut. No individual differences in the color gamut of the nine lights were found. Because the luminance input values were not linear, color calibration was performed individually.
To examine the effects of multiple colors, we conducted an experiment. The lighting was set up so that the three lights installed in the center of the room were directed at the center and the observer was directly irradiated, as shown in Fig. 4. The space was designed so that the observers could employ both central and peripheral vision to see the opponent color, regardless of where they were sitting, by irradiating the wall with the remaining six opponent colors.
In this study, we assumed that the opponent color also belongs to the higher ranking of the 45 recall colors. Table 2 shows the degree of association between the recall color and the adjective. In Table 1, we used the yellow recall color for “happy,” but there was no opponent color for yellow in the upper recall color for “happy.” Therefore, pink, which is another upper recall color for “happy,” was used in the experiment. We then examined three types of lighting mixtures of opponent colors (a) to (c) and single uniform lighting (d) for comparison as follows: (a) Pink and nearest opponent color within 45 colors (b) (b-1) Pink and opponent color in sRGB color space
(b-2) Yellow and opponent color in sRGB color space (c) (c-1) Pink and opponent color in L*a*b* color space
(c-2) Yellow and opponent color in L*a*b* color space (d) (d-1) Single pink color
(d-2) Single yellow color In addition, each lighting color was alternated between the central and peripheral vision. Table 3 summarizes the lighting combinations with L*a*b* values.
Lighting type (a) (b-1) (b-2) (c-1) (c-2) (d) Scenario 1 Scenario 2
Central vision
In this experiment, two observers (A and B) had a short conversation based on scenarios
meant to induce a “happy” emotional state. Table 4 shows the scenarios selected from
[
The observers who participated in the experiment comprised three groups of university students, aged from 22 to 25 years, four of whom were males and two were females. Each group consisted of two readers and evaluated 10 adjective pairs, including “happy-sad,” using a five-point SD scale. Table 5 shows the adjective pairs, which were arranged in the same order on the evaluation form.
To confirm the emotions induced by the scenarios, the observers first read the two scenarios silently under 180 lx white light and evaluated the impressions they received only from the sentences they read. Then, for each adjective, one color was randomly selected from among the 12 combinations of colors shown in Table 3. After 10 seconds, the adaptation time after illumination, the observers were asked to discuss the scenario. After the discussion, we switched back to white light to eliminate the effects of the previous color, and then evaluated the emotion using the SD method.
After the evaluation was completed, the LED lights were switched to the next color. The same procedure was repeated for the two scenarios under each of the 12 lighting colors, resulting in a total of 24 evaluations. All evaluations were carried out for 30 minutes without a break.
First, we verified that the scenarios used in this experiment induced the desired emotional state. The average factor scores for the impression "happy" obtained from only reading the scenario were 1.50 and 1.17 for scenario 1 and scenario 2, respectively. A positive value means that the conversation scenario correctly induced the emotion represented by "happy."
Next, a factor analysis was performed on the 10 adjective pairs used in the SD method, and common factors were extracted. As shown in Table 6, the variables were classified into three factors, “favorability,” “freshness,” and “grade.” Because the purpose of this study is to promote empathy regarding positive emotions, we discuss the scores of the adjective pair “happy-sad” and its corresponding factor “favorability” for each lighting combination.
Adjective pair hard-soft like-dislike safe-uneasy relaxed-nervous happy-sad quiet-noisy clear-cloudy luxury-common
open-closed comfortable-uncomfortable
The average evaluation values of “happy-sad” for each irradiation are shown in Table 7. By irradiating the peripheral vision color with the higher recall color, all combination irradiations (a)–(c) of the opponent colors were found to be higher for “happy” than for single color irradiation (d). In particular, coloration (a) was evaluated as stable and high even when the central and peripheral visual colors were switched. This result suggests that a positive “happy” emotion is promoted by spatially combining the recall color and its opponent color corresponding to the emotion.
For “favorability,” the evaluation is not as clear as the adjectives because the factor includes six adjective pairs. However, as shown in Table 8, it can be confirmed that the evaluation for a single yellow color was low, but the results for combination irradiations of opposite colors were generally high. Lighting type (c-2) (d) Lighting type
We set up an environment that induces a specific emotional state through conversation and conducted psychophysical experiments to investigate the lighting conditions that promote a positive emotional state. Physiological findings showed an excitatory response with opponent colors in the central and peripheral receptive fields of ganglion cells and verified the effect of spatial opponent color irradiation. The experimental results suggest that a positive emotion such as “happy” is promoted by spatially combining the recall color corresponding to the emotion and its opponent color, specifically by irradiating the surroundings with the recall color and the center with the opponent color.
In future, it is necessary to study emotion control using lighting colors for more emotions.