The effects of correlated colour temperature on wayfinding performance and emotional reactions

The effects of correlated colour temperature

on wayfinding performance and emotional

reactions

Ozge Kumoglu Suzer and Nilgun Olgunturk

This study investigated travellers’ wayfinding performance according to the correlated colour temperature (CCT) of lighting in a virtual airport environ-ment. In the first phase an experiment was conducted under 3000K (yellowish-white) and 12000K (bluish-(yellowish-white) light. Universal face representations of basic emotions (anger, disgust, neutral, surprise, happiness, fear, sadness) were shown to participants and they were asked to choose a single face. In the second phase, two questionnaires were conducted to identify participants’ level of presence in the virtual environment. Females were significantly more lacking in confidence than males in finding their destination, hesitating more often. The results indicated that participants’ wayfinding performance was better under 12000K, which they also associated with more positive emotion.

Keywords: wayfinding, emotion, colour temperature, lighting, virtual environment

1. Introduction

Wayfinding is the “consistent use and organization of sensory cues from the exter-nal environment in order to reach a desired destination” (Lynch 1960). Arthur and Passini (1992) explained wayfinding as a spatial problem-solving activity compris-ing three specific but interrelated processes: decision makcompris-ing (and the development of a plan of action), decision execution (transforming the plan into appropriate behaviour at the right time and place), and information processing (environmental perception and cognition, which are responsible for the information basis of the two decision-related processes). According to Abu-Obeid (1998), perception and cognition are the two basic components of information processing, upon which the processes of making and executing decisions are built. On the other hand, Løvs

(1998) described wayfinding as a hierarchical decision process in which people first select their goal, and then they select a destination and then a route to follow.

Arthur and Passini (1992) defined cognitive mapping as part of environmen-tal perception where cognition provides the source of information from which to make and execute decisions. Perception is defined as the process of obtaining information through the senses; whereas cognition is defined as understanding and being able to manipulate information. Obtaining information is not enough to be able to find one’s way, as understanding and manipulating the information is also an essential part of wayfinding. Arthur and Passini (1992) defined the cogni-tive map as “an overall mental image or representation of the spaces and the layout of a setting” and cognitive mapping as “the mental structuring process leading to the creation of a cognitive map”. Lynch (1960) suggested that cognitive maps are developed for wayfinding tasks. Garling et al. (1984) suggested that cognitive maps should contain not only spatial knowledge, but also action and travel plans to facilitate wayfinding performance. Kitchen (1994) suggested that cognitive maps are used to solve spatial problems such as wayfinding and navigation.

Chen and Stanney (1999) suggested a more elaborated version of Arthur and Passini’s (1992) theoretical model of wayfinding process as divided into three sub-processes: cognitive mapping, decision making (wayfinding plan development), and decision executing (physical movement or navigation through an environment). The model delineates the wayfinding process, including the distinct influences of spatial information, spatial orientation, and spatial knowledge. The influences of experience, abilities, search strategies, motivation and environmental layout are also considered.

According to the Chen and Stanney’s (1999) wayfinding model, wayfinders generally commence by directly perceiving the environment or working from a cognitive map. The integration of three types of spatial knowledge (landmark, procedure, and survey) generates a cognitive map. Beyond spatial knowledge, cognitive maps may also contain wayfinding decisions and plans. After a cognitive map has been generated, the second step in the wayfinding process is decision-making. This involves using the cognitive map information generated in the first step to guide the development of wayfinding plans, followed by a decision execu-tion process, in which navigaexecu-tion commences. These steps can be repeated several times until the target destination is reached.

Emotions influence attention, decision making, and memory, which are all factors required for wayfinding. Balaban et al. (2014) found that emotional state and emotionally laden landmarks have an impact on wayfinding. Damasio et al. (1996) stated that there is a connection between emotion and cognition in practi-cal decision making. Izard (1977) reported that emotion affects the wayfinder’s memory, thinking, and imagination. Parkinson (1997) stated that emotions are

considered to be evaluative, affective, intentional, and short-term conditions. The term emotion cannot be described completely by having a person describe his/ her emotional experiences; by electrophysiological measures of occurrences in the brain, the nervous system, or in the circulatory, respiratory, and glandular systems; or, by the expressive patterns or motor behaviours that occur as a result of emo-tions. A complete definition of emotion must take into account the three aspects or components as:

(a) The experience or conscious feeling of emotion,

(b) The processes that occur in the brain and nervous system,

(c) The observable expressive patterns of emotions particularly those on the face. Light is an important physical factor influencing space perception, and may also affect users’ emotional reactions. Moreover, light has a considerable effect on how people perceive the physical qualities of a space, and light gives meaning and emo-tion to that space (Knez 1995). The effect of lighting on people’s emoemo-tions is an important factor in providing better interior spaces. Therefore, lighting should be considered as an essential design element, along with form, colour, and texture, and therefore as a significant contributor to spatial compositions.

Lighting can also play an important role in mood, health, performance, and social behaviour. Lighting affects every part of our lives, and has an impact on hu-man beings psychologically and physiologically. Colour temperature is an aspect of lighting, affecting its appearance. This effect is especially noted in white light, which ranges from a very cool white to a very warm white (Flynn et al., 1988). Any light source whose chromaticity coordinates fall directly on the Planckian locus has a colour temperature equal to the temperature of the blackbody radiator that radiates light of comparable hue. For light sources whose chromaticity coordinates do not fall exactly on the Planckian locus but do lie near it, correlated colour temperature (CCT) is used. The CCT can be determined by extending an isotemperature line from the Planckian locus to the chromaticity coordinates of the light source.

There is much research on the effects of lighting and CCT in interior spaces (Biner & Butler 1989; Bornstein 1975; Boyce & Cuttle 1990; Davis & Ginthner 1990; Fleischer et  al. 2001; Rea 2000; Knez 1995; Manav & Yener 1999; Odabaşıoğlu & Olguntürk 2015; Taylor & Socov 1974; Tiller & Veitch 1995). These studies report a significant effect of lighting on perception, the impression of spaciousness, space evaluation, physiological and psychological comfort, spatial orientation, and wayfinding. There is also much research on the effects of CCT on performance (Hidayetoğlu et al. 2012; Van Hoof et al. 2009; Knez 1995; Knez & Kers 2000; Manav & Küçükdoğu 2006), such as in long-term recall, recognition tasks, problem-solving tasks, free-recall tasks, performance appraisal tasks, mood, spatial perception, and memory.

It is important to design task lighting according to a user’s emotional reac-tions. When designing with light, living environments should be analysed as they may influence human reactions, psychologically and physiologically. This is called the “emotionally ergonomic approach to design” (Jin et al. 2009). Therefore, this research investigation was based on a conscious endeavour to demonstrate the relationship between lighting and emotion, specifically in interior environments.

To the authors’ knowledge there is no previous research in the literature studying the relationship between CCT and wayfinding performance. Exploring this relationship is important because any significant effect could change users’ performance in high-density, stressful environments, where white artificial light-ing is extensively used, such as airports. Suzer et al. (2018) discovered the effects of CCT on wayfinding performance in a virtual airport environment. The experi-ment was conducted with three different colour temperatures of lighting: 3000K, 6500K and 12000K. It was found that CCT has no significant effect on wayfinding performance in terms of time spent, the total number of error, the total number of decision points and the route choice during finding the route. However, the CCT did have a significant effect on hesitation in decision making. It was found that the total number of hesitations decreased when the CCT increased from 3000K to 12000K. Gender difference was also explored regarding this study, and females were found to be significantly less confident than males in finding their final des-tination, hesitating more often. Therefore, the previous study furthered the body of knowledge on wayfinding performance through the emotional reactions of females. This further study aims to fill the gap in wayfinding and lighting research, exploring the effect of CCT on emotional reactions and wayfinding performance.

Figure 1. Partial plan of the virtual airport building, showing participants’ selected routes (green line: short route, blue line: long route)

2. The experiment

The hypotheses of this study are:

1. A high CCT value improves participants’ wayfinding performance.

2. Participants associate a space with a more positive emotion when viewed under a CCT with high value.

2.1 Participants

The volunteer participant group consisted of 60 undergraduate female students, with a mean age of 22 years (stdev = 2.66). The experiment was conducted with two different sample groups: 30 females for experiment set 1, and 30 females for experiment set 2.

2.2 Modelling

Controlling CCT of lighting throughout an airport is only possible in a virtual environment (VE), thus for this research, 3D Studio Max was used for modelling. The Mental Ray renderer was used to adjust CCT and illuminance levels, as it is the only renderer that can perform these tasks scientifically. In the virtual airport, 35 cameras were located every six metres (Figure 1). To simulate these, 35 images were rendered for each experimental setting and presented to the participants through a slide show.

2.3 Experiment sets

The only difference between the two experimental settings was in lighting CCT. The researcher controlled the Red, Green, Blue (RGB) colour values of the display and kept illuminance level and space organization constant for both settings. In the first setting, lighting CCT was set to 3000K (yellowish-white). In the second setting, CCT was set to 12000K (bluish-white) (see Figures 2 and 3).

Figure 2. Virtual environment illuminated with 3000K CCT at 200 lux

Figure 3. Virtual environment illuminated with 12000K CCT at 200 lux 2.4 Procedure

The study was conducted in two phases. In the first phase, participants sat at the computer display in a darkened room, and were tested individually by the researcher. A single LCD screen of 10.1” diagonal was used, and calibrated as fol-lows: gamma, 1.0; brightness, 0; contrast, 50. The screen resolution was 1024x600 and the colour quality was 24-bit. An explanation of the virtual environment was

first read to each participant: “Here is an airport. We will start our tour from the entrance, and the gate numbered 109 is the destination. Please direct me after each image with one of the expressions of ‘go right/left/forward/back’.” During the experiment, the participant could hear the background noise of an airport through earphones to provide a sense of place. At each step, corresponding to an increment of six metres in the VE, the researcher changed the image accord-ing to the participant’s verbal directions until he or she reached the destination. Throughout the experiment, the participant’s directions given, errors, hesitations and time spent were all recorded. Then the participant was shown photographs of faces from Ekman et al. (2013), which are universal representations of basic emotions (Figure 4), and was asked to choose a single face representing a specific emotion that best fitted the experience of the VE. The corresponding names of the emotions were not shown to participants.

Anger Disgust Neutral Surprise Happiness Fear Sadness

Figure 4. Facial expressions of emotion used in study (Ekman et al. 2013)

In the second phase, two questionnaires were administered to each participant – one to assess the sense of presence within the VE and the other to assess prior experience with computers. The assessment of sense of presence was important because the participants had to feel present in order to orient themselves correctly. The effectiveness of VEs has often been linked to the sense of presence reported by users. (Presence is defined as the subjective experience of being in one place or environment, even when one is physically situated in another.) The English version of the Igroup Presence Questionnaire (IPQ) developed by Schubert et al. (2001) was used for this study. Every participant had a certificate of proficiency in English. In the first survey, participants answered questions from the IPQ, a scale for measuring the sense of presence experienced in a VE, and consisting of 14 items rated on a seven-point Likert scale. The items include one general item, five items on ‘spatial presence’, four items on ‘involvement’ and four items on ‘realness’. The second survey aimed to identify participants’ familiarity with computers. All participants reported that they felt present and that they were familiar with computers at similar levels.

3. Findings

3.1 Effect of CCT on wayfinding performance

The effects of CCT on wayfinding performance were evaluated and analysed for the following three criteria:

1. Time spent in finding the destination: The researcher recorded how long it took each participant to reach the destination. The researcher assessed time spent in finding the destination for the two sample groups, i.e. the two experiments of Set 1 (3000K CCT) and Set 2 (12000K CCT), by comparing the durations of the wayfinding task. As the frequency had a skewed distribution, the research-er used the Kruskal Wallis one-way analysis-of-variance test (mean = 138.78, stdev = 56.05, n = 60). The results indicated that the effect of CCT on time spent in wayfinding was not significant (χ2 = 0.85, df = 1, p = 0.35).

2. Number of errors in finding the final destination: Each wrong turn was regarded as an “error” in this study. When the participants went in the wrong direction, the researcher informed them of the mistake, directed them to the previous image, and asked them to decide again. This process was repeated at every wrong turn until the destination was reached. The researcher noted each error point on the experiment sheet. The number of errors in finding the destination was assessed by Kruskal Wallis’ one-way analysis-of-variance (mean = 1.03, stdev = 0.88, n = 60) (see Figure 5). The results indicated that the main effect of CCT on the total number of errors was statistically significant (χ2 = 4.97, df = 1, p = 0.02). The proportion of variability in the ranked dependent vari-able (number of errors) accounted for by the CCT varivari-able was 0.08. In the 12000K CCT condition, participants made significantly fewer wrong turns and were more successful in finding their way.

3. Number of hesitation points in finding the final destination: Beusmans et al. (1995) recorded reaction times for direction responses to be three seconds maximum. Hence, for this study, participants who paused for more than three seconds at a decision point were considered to be experiencing hesitation. The number of hesitation points in finding the destination by the two sample groups were assessed by comparing the total number of hesitations in the wayfinding task. These reflect all 30 participants’ total numbers of hesitation points for each setting (mean = 1.73, stdev = 1.20, n = 60) (see Figure 5). The Kruskal Wallis test indicated that there was a significant difference between the two groups in terms of the total number of hesitation points (χ2 = 16.51, df = 1, p = 0.00). The proportion of variability in the ranked dependent vari-able (number of hesitation points) accounted for by the CCT varivari-able was 0.27,

indicating a definite relationship between CCT and the number of hesitation points. In 12000K setting, participants hesitated significantly less often than in the 3000K setting. 0 5 10 15 0 5 10 15 4 0 1 2 2 4 2 1 0 3000k 12000k CCT Coun t Coun t error hesitation

Figure 5. Bar charts showing the frequencies of error and hesitation points in the two settings

3.2 Effect of lighting CCT on emotional reactions

According to the result of Spearman’s Rho correlation test, there was a significant positive correlation between lighting CCT and emotional reactions (r = 0.43, at 0.01 level, two tailed). Thus, participants experiencing the VE illuminated by 3000K lighting (warm white) more often associated it with neutral emotion. However, participants experiencing the VE illuminated by 12000K lighting (cool white) more often associated it with an emotion of happiness (see Figure 6 and Table 1).

0 5 10 15 20 25 0 5 10 15 20 25 _anger disgust neutral surprise happiness fear sadness emotion 3000k CCT 12000k

Figure 6. Incidence of emotions associated with the two settings.

Table 1. Frequency of emotional reactions in the two settings CCT Total 3000k 12000k emotion anger 5 0 5 disgust 2 0 2 neutral 15 5 20 happiness 2 21 23 sadness 6 4 10 Total 30 30 60 4. Discussion

This study investigated the effect of CCT on emotional reactions and wayfinding in a virtual airport environment. Participants’ emotional reactions and wayfinding performances were compared under CCTs of 3000K and 12000 K. The hypothesis was that there would be different emotional reactions and wayfinding perfor-mance depending on the CCT. It was found that CCT has no significant effect on wayfinding performance in terms of time spent. However, CCT does have a significant effect on making errors and experiencing hesitations. The total number of errors and hesitations decreased when CCT changed from 3000K (warm white) to 12000K (cool white).

This study can be regarded as an extension of the previous study done by Suzer et al. (2018), in which the effects of CCT on wayfinding performance in a virtual airport environment were investigated by an experiment with three lighting set-tings of 3000K, 6500K, and 12000K. It was found that the CCT had a significant effect on experiencing hesitations. The total number of hesitations decreases for a CCT of 12000K. In addition, females were significantly less confident than males in finding their final destination, hesitating more often. Therefore, the current study furthers the body of knowledge with wayfinding performance through emotional reactions of females in relation to the CCT of lighting. The results indicate that participants’ wayfinding performance was better under 12000K, which they also associated with a more positive emotion compared to 3000K.

Studies exploring the relationship between wayfinding performance and emo-tion have been very limited. The findings of the current study confirm those of Balaban et al. (2014), who found that both an emotional state and emotionally laden landmarks have an impact on wayfinding and on later recollection of the path. They showed that emotions had no significant effect on correct recognition,

wayfinding and response times. Besides, they also explored that emotionally laden landmarks were remembered better and were associated with shorter response times (i.e. less hesitation) than neutral landmarks. The current study was not focused on landmarks, but the two studies are comparable in terms of the wayfind-ing performance and emotions.

Travelling can be one of the most stressful wayfinding processes, causing travellers to experience psychological and physiological reactions when they feel disoriented. Determining why travellers hesitate more under 3000K CCT is im-portant to enhance the wayfinding experience. This study found that according to the result of Spearman’s Rho correlation test, there was a high positive correlation between lighting CCT and emotional reactions (r = 0.43, at 0.01 level, two tailed). Participants experiencing the VE with 3000K lighting associated the airport space with neutral emotions. However, participants experiencing the VE with 12000K lighting associated the space with the emotion of happiness.

Furthermore, in this study, according to the result of the Spearman Correlation test, a significant medium level of correlation was found between emotional reac-tions and involvement (r = 0.740, at 0.05 level, two tailed). The more the partici-pants feel involved, the more emotion they associate as happiness. However, if the participants do not feel involved, they associate neutral emotion. There were no correlations found between emotional reactions and general sense of presence, spatial presence and realness. Finding correlations just between emotional reac-tions and involvement in this study, may be a comparable issue for future studies. Moreover, there were no correlations between the CCT of lighting and general sense of presence, spatial presence and realness. Conversely, according to the result of Spearman Correlation test, the CCT of lighting and involvement were in posi-tive correlation (r = 0.77, at 0.01 level, two tailed). The 3000K lighting decreased the level of feeling involved in the VE, however, the 12000K lighting increased the level of involvement.

According to all the results from this study, a virtual airport environment il-luminated by 12000K lighting was associated with the emotion of happiness, and also increased the sense of presence in terms of involvement. Conversely, the same virtual airport environment illuminated by 3000K lighting was associated with neutral emotion, and also decreased the sense of presence.

5. Conclusion

In the literature, CCT studies mostly concentrate on perception, individual liking, work performance, and psychological and physiological effects. As airports are one of the most important public spaces in today’s globalized world, it is important to

analyse the type of environment provided for travellers. In such settings, passenger circulation and wayfinding are prominent issues. The findings of this experiment may be beneficial not only for interior architects but also for environmental psychologists, who may be interested in different factors affecting user behaviour. Further studies should be conducted in order to understand the effects of CCT on wayfinding, and to explore the effects of CCT on human behaviour. In this study, the effect of CCT on travellers’ wayfinding performance was gauged by emotional reactions, however there may be other types of reactions, and these should be investigated.

This study could be seen as an initial stage of exploring the cognitive perfor-mance of wayfinding with the effects of lighting and emotional reactions. Gender difference should also be considered for further studies with a large participant group. This is still a controversial issue in the literature, not only in wayfinding but also in spatial ability in general (Voyer et al. 1995). Although gender differences were not uniformly found, when they were found they often favoured males (Allen & Hogeland 1978; McGee 1979; Linn & Petersen 1985). Thus, it is still not known in the literature, how individuals of different gender react emotionally to lighting and how that affects cognitive performance of tasks such as wayfinding.

For this study, because of technological limitations, a slide presentation meth-od (passive virtual environment) was used to assess the wayfinding performance of travellers in a virtual airport environment. However, for further studies we recommend that researchers use interactive “walkable” 3D virtual environments in order to conduct a more reliable experiment. Moreover, head-mounted displays were found unreliable in previous wayfinding studies because of their low display resolution, small field of view, sickness sensation, etc. (Vilar & Rebelo 2008). However, the rapid development of head-mounted technologies in recent years has significantly opened the way for environmental psychologists to focus on the research area of wayfinding.

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