Designing for Hope: Biophilic Color Associations and Their Relevance to Clinical Settings

Significance

The present study deliberately considered only one common BD element (i.e., color) and one important characteristic of well-being (i.e., hope). This approach not only has the advantage of reducing confounds but can also give to practitioners a clearer sense of what to emphasize in their design work.

Although all of our senses have biophilic value vision, from an evolutionary perspective, has particular importance given that it permits effective foraging among other survival-based behaviors. It may even be regarded as our primary sense (Sun, 2019). One prominent aspect of vision is color perception. What’s more, colors have the ability to elicit strong emotional responses including positive states consistent with an experience of well-being (Simmons, 2011). Indeed, color field painters deliberately seek to elicit strong emotions from viewers (e.g., Mark Rothko; Bedworth 2023). However, color perception is complex (Corney et al., 2009; Heerkens, n.d.), key aspects of emotion remain debated (Barrett et al., 2016), and any association between the two may be confounded by personal and cultural preferences (Mohr et al., 2018). Nevertheless, colors with biophilic significance are likely to be more robust to personal and cultural confounds.

Well-being is an umbrella term under which many of our aspirations for “the good life” are placed (Alexandrova & Fabian, 2022). Even so, hope represents an important psychological component of well-being (Slezackova, 2017). Although hope has cognitive, affective, behavioral, relational, cultural, and even existential elements, it is nevertheless fundamentally motivational directing us to achieve future goals (Edwards & Chiera, 2021; Edwards & Jovanovski, 2016; Snyder, 2002). However, in the present context, hope’s value lies in the fact that it is an important clinical adjunct across multiple medical/surgical specialties (Kube et al., 2019) while holding special significance in rehabilitation (Brazeau & Davis, 2018), oncology (Corn et al., 2020), palliative care (Kylmä et al., 2009), and mental health (Edwards & Jovanovski, 2016) settings. Hope, therefore, not only promotes well-being but is a vital aspect of holistic healthcare.

Aim

In spite of the difficulties in studying color, hope, and any potential association between them, the biophilia hypothesis (Wilson, 1984) represents a strong unifying framework for it is rooted in evolutionary biology (Barbiero & Berto, 2021). Not only are hope and color vision the product of our psychobiology but are also subject to selection pressure (Jacobs, 2009; Nesse, 1999; Schaller et al., 2017). As such, there is an underlying coherence in the biophilic study of hope and color vision. In fact, both hope and color vision may be sensitive to selection pressures associated with foraging. Finally, in spite of Heekens’s (n.d.) reservation that “green…is not a color of great emotion”, the author hypothesizes that green, being the quintessential biophilic color, will evoke a strong experience of hope (Kaya & Epps, 2004; Reed, 2021).

Sample

Participants were 154 healthy adult volunteers. The sample was recruited opportunistically from the student body of the author’s institution. In line with ethical standards no inducements were offered to participants and the author remained independent of the recruitment and testing process. Following institutional ethics approval recruitment and testing were performed by research students trained for the task by the author (see Acknowledgment section). Recruitment occurred using a two-step process. Participants contacted the research team having seen an on-campus advert, having been informed of the research project through a class announcement, or having informally been alerted by a peer. Once contact was made with the research team an appointment was arranged. The appointment was divided into two time periods: (1) for screening which completed recruitment; and (2) for testing. To maintain participant anonymity and to limit psychosocial confounds each participant was unknown to the researcher who performed their preexperimental screen and subsequent data collection.

Excluding a small number of nonresponses for gender and/or age, females constituted 53% of the sample which had a mean age of 39.6 years. In addition, the sample was predominantly formed from people of Anglo-Australian heritage. Although the study’s inclusion criteria specified healthy adult volunteers its exclusion criteria pertained to screening participants for: (1) color blindness using HRR pseudoisochromatic plates (Bailey et al., 2004); and (2) an “abnormal” level of hope (i.e., low/high) assessed using the Adult Hope Scale (Snyder et al., 1991), presented as “The Future Scale,” and scored out of a possible 64 points. Given limited clinical data to assist in identifying people with an “abnormal” level of hope versus simply high hope individuals, and recognizing that on this scale people often score higher than 50% (Snyder et al., 1991), exclusions suggested by the Adult Hope Scale (i.e., scores nominally ≤24 or ≥60) were confirmed only having also gleaned and assessed the following information: (1) Did the participant have a medical issue which may have impacted their hope score?; (2) Was the participant having a normal day?; and (3) What was the participant’s present state level of hope scored out of 5? Excluded participants were debriefed in accordance with best practice.

Study Design

All experiments occurred under standard conditions to reduce perceptual confounds. Participants were tested one at a time in a quiet dedicated testing room painted in a shade of white. Each participant completed their task seated at a small table which had a matt white surface. A single ceiling fluorescent light gently illuminated the room. The experimenter sat diagonally behind each participant to reduce any socioemotional confounds which may have resulted from personal interactions. The experimenter also sat outside the participant’s “body space” to negate any social discomfort. Nevertheless, the possibility of residual social discomfort cannot be excluded and future studies may seek to omit the experimenter from the room and/or alter where the participant sat (e.g., at the room’s perimeter).

On the table was placed either a stack of test cards (i.e., Experiments #1 and #2) or a single test card (i.e., Experiment #3). Experiment #2 used two stacks of test cards, one stack at a time. When a stack of test cards was used it was set to the side of the participant slightly outside their visual field to reduce perceptual confounds. To remove order effects test cards within a stack were randomized for each participant. If two stacks of test cards were to be presented to a participant their order was also randomized. Each test card was A4 in size. One test card at a time was examined. Each participant did so by placing it on the table surface in front of themselves.

Test cards were illuminated evenly by a white Brilliant Lighting (#99190) 11 W fluorescent lamp. The lamp used a 6,400 K fluorescent tube (220–240 V, 11 W). The lamp was placed on the table opposite the participant. This eliminated the confound of shadow. The lamp’s shade also precluded perceptual errors and/or visual illusions associated with bright light.

Experiment #1 utilized 44 participants and sought to ascertain which color, from a selection of four biophilic colors, most strongly evoked an experience of hope. Based upon the biologically derived Natural Color System^® the colors red, yellow, green, and blue were chosen. These colors being closely aligned to natural phenomena with biological relevance and therefore having evolutionary significance. The cards shown to participants were sourced from Quill Stationery Manufacturers Pty. Ltd. who used the proprietary labels: Red, Lemon, Emerald Green, and Royal Blue (https://quillpaper.com.au/). Participants rated each test card for its relative ability to evoke hope.

Using the RGB (red, green, blue) color model, Experiment #2 sought to determine the effect of color depth in evoking hope. In brief, the RGB model is a three-dimensional color model whereby hues can be specified using values between 0 and 255 for red (R), green (G), and blue (B). As such, the RGB color model manipulates color within a cube whose eight vertices are represented by green, yellow, white, cyan, black, red, magenta, and blue (Wagner, n.d.). To avoid the introduction of confounding hues maximal color depth yellow (R = 255, G = 255, B = 0) was manipulated “on the diagonal” between achromatic black (R = 0, G = 0, B = 0) and achromatic white (R = 255, G = 255, B = 255). This implied two independent manipulations and therefore the generation of two sets of test cards. In the first manipulation, R and G values decreased while B was set at 0. In the second manipulation, the value for B was increased while R and G values were set at 255. To maintain “yellowness” R and G values were not shifted lower than 155, nor B values shifted above 225.

Ultimately, 75 participants were presented with two stacks of test cards. Each stack had five test cards within it. Although both stacks had one test card representing maximal color depth yellow all other test cards differed in their color depth. Considering one stack at a time, participants rated each test card according to its relative ability to evoke hope.

Experiment #3 sought to determine if Experiments #1 and #2 had been confounded by priming participants for hope. To ascertain if priming had occurred participants were now presented with the test card found to be the most evocative in Experiment #2. In so far as hope may be described as an emotion 35 participants were asked to reflect and report on what emotion this single test card evoked. To minimize the potential for extreme semantic diversity among responses (Cowen & Keltner, 2017) the author had each participant limit their choice to one of Plutchik’s eight evolutionarily derived basic emotions (Plutchik & Kellerman, 1980).

Finally, to account for personal/cultural confounds all participants were asked to nominate their most/least favorite color and any color associations they may have.

Experiment #1

This investigation sought to establish which of four biophilic colors evoked the greatest experience of hope. Thirty three of 44 participants considered the yellow test card to evoke the strongest experience of hope. This compared to five participants who chose the red test card, three participants who chose the blue test card, and three participants who chose the green test card. To demonstrate the clarity of this finding a single chi-square analysis comparing yellow preference to the combined preference of the other colors was performed, χ²(1, N = 44) = 11.00, p < .001.

Experiment #2

When R/G values were decreased 61, out of 75, participants chose that test card displaying maximum color depth yellow as evoking the strongest experience of hope. Again, given the clarity of this finding, a single chi-square analysis comparing those participants who preferenced maximal color depth yellow against the combined preferences for all other shades was performed, that is, χ²(1, N = 75) = 29.45, p < .001.

Similarly, when B values were increased 54 participants chose that test card displaying maximal color depth yellow as evoking the strongest experience of hope. As above, the clarity of this finding suggested a single chi-square analysis comparing those participants who preferenced maximal color depth yellow against the combined preferences for all other shades, that is, χ²(1, N = 75) = 14.52, p < .001.

Experiment #3

Participants were provided with a single test card displaying maximum color depth yellow. Twenty four of 35 participants stated that this test card evoked “joy.” This result is not surprising given that joy and hope are positive affective states and share a common biological basis being the dopaminergic neurotransmitter system (Gu et al., 2019). Although Plutchik did not engage hope per se, he did align optimism with joy through the latter’s dyadic relationship with anticipation, while Parrott (2001) actually placed hope within the broader emotion category of joy (Abbasi & Beltiukov, 2020). A single chi-square analysis comparing those participants who named joy against the combined basic emotion preferences of the remaining participants was performed, χ²(1, N = 35) = 4.83, p < .05.

Personal/Cultural Confounds

No participant nominated yellow as their most/least favorite color. No participant nominated a strong cultural association with any of the four biophilic colors presented in Experiment #1. Green, blue, and yellow all elicited strong biophilic associations. Yellow was associated with the “sun” or “sunshine,” green with “new life,” and blue with the “open sky.” Red did not evoke descriptions of the natural world but, instead, elicited strong emotions such as “passion” and “anger.”

Limitations and Research Recommendations

The present study, although accounting for numerous perceptual and psychological confounds, was methodologically limited. That color perception is both complex and subtle (Albers, 2013; Corney et al., 2009; Heerkens, n.d.), and may even be influenced by one’s health status (Park, 2009), suggests the need for further investigations which engage technically demanding methodologies. Such methodologies must be able to: (1) precisely manipulate color qualities (e.g., hue, saturation, and brightness); (2) account for differences in perception according to the type of illumination used (e.g., fluorescent lights vs. daylight, or even direct sunlight); and (3) engage participants who are also healthcare users. To this end, future studies will seek to use a simulated environment whether at scale (e.g., 1:12; Park, 2009; Park & Park, 2013) or as a purpose-designed room in which salient environmental factors can be controlled (Harleman, 2004). By the by, and consistent with the present findings, when Harleman (2004) used a purpose-built room to assess the relationship between color perception and affect they found that “reddish yellow … caused the strongest positive reactions of all colours” (p. 225).

While the visual environment impacts health and well-being (Salonen et al., 2013), the role of color remains contested in spite of multiple psychological explanations (Fernandez-Caballero et al., 2016). One influential review by Tofle et al. (2004) not only concluded “no direct linkages between particular colors and health outcomes” but described as “unsubstantiated” current beliefs about color-mood associations, while any attempt to provide guidelines as to color-mood associations in healthcare settings was “futile” (pp. 4–5). Although definitive in tone, it must be recognized that this review was a synthesis of more than 3,000 studies across diverse scientific and social science disciplines all of which have their own traditions, ways of expression, methods, and burdens of proof. In essence, the authors set themselves an Herculean task but, in doing so, could not be expected to engage deeply with the implications of the many nuances of their source literature. For example, in spite of their conclusions, Tofle et al. (2004) noted eight studies which clearly demonstrated red to be physiologically arousing. Furthermore, Tofle et al. (2004) did not directly engage an evolutionary perspective as was done in the current paper. So while the author agrees that some individual variation exists with respect to color-affect associations he questions the value of Tofle et al.’s (2004) conclusions to the current work.

By contrast, Ghamari and Amor (2016) conceded that the literature was both fragmented and contradictory, nor were they dismissive of the importance of color in healthcare environments. While accepting the relevance of personal and cultural factors, they recognized that: (1) a red/blue themed work environment, alongside task demand, may influence workplace measures by arousing/calming staff; (2) well lit “colored rooms with balanced tension” (p. 1024) could reduce clinical mistakes; (3) orange walls in a patient’s room had an arousing effect compared to green, especially when a patient was unable to effectively screen out a distracting environment (Dijkstra et al., 2008); and (4) different colors affected the passage of time which has well-being implications for patients undergoing a protracted hospitalization (i.e., red is associated with shorter time estimates).

As to research recommendations, future investigations should also consider the experience of perceiving: (1) two biophilic colors in juxtaposition; (2) one biophilic color in juxtaposition with a nonbiophilic color; and (3) one biophilic color in juxtaposition with various achromatic colors. The importance of which comes about as contemporary hospital design often incorporates all three possibilities (Online Editor, 2014, November 14; Ulrich, 2001).

For mental health researchers, the present study also offers opportunities as hopelessness correlates with depression (Edwards & Jovanovski, 2016). What’s more, the author, being also a clinician, is aware of a middle-aged male whose depression was accompanied by a dulling of his color vision. Such observations in concert with the present findings support the development of novel methods of depression assessment and treatment. For example, it is not unreasonable to consider if depression severity could be gaged by color perception. Similarly, a novel treatment for depression may be to mimic light-box therapy as currently used for seasonal affective disorder—albeit now tuning a light box, or even the ambient light within a patient’s room, to a yellow hue (Fernandez-Caballero et al., 2016). However, this presumes that exposure to yellow light could instill a sense of hope which may be subtly different from evoking an experience of hope.

The present findings also hint at a candidate neurology of hope by implicating a brain circuit which links color vision with key aspects of hope such as positive affect, a future focus (Edwards & Jovanovski, 2016; Snyder, 2002), and a storied account of suffering (Mair, 1989; Wright, 2012). Van de Ven et al. (2013) have linked the affective serotonergic neurotransmitter system to the brain’s default mode network (DMN) which is also implicated in the construction of one’s self-story and personal future (Xu et al., 2016). Other studies have also shown the DMN to interact with the visual system in various ways (Szinte & Knapen, 2020; Vessel et al., 2019; Violante et al., 2012).

Finally, and somewhat speculatively, the present findings have relevance for evolutionary psychologists. Premised on the belief that cues in the environment signal particular internal motive states which, in turn, give rise to various cognitions/emotions/behaviors (Davis & Montag, 2019), it is not unreasonable to consider color to be such a cue. There is also some evidence to suggest that certain colors signal specific motive states (Buechner et al., 2014).

At a minimum, an animal that has to compete for resources requires three motive states. First, there is the need for a present-focused high motivation state underlying the ability to fend-off competitors and secure resources. This is akin to a state of alertness and displays of dominance. Second, when resources are plentiful, a low motivation state allows an animal to rest and recuperate. This being a necessary and beneficial psychophysiological state associated with a host of reparative functions and prosocial behaviors. Third, many environments are resource poor. To secure adequate resources an animal needs to maintain a highly motive state over the longer-term, suggesting an awareness of future reward.

The author posits that the four biophilic colors tested in Experiment #1 have the capacity to signal these three motive states. Red heralds an attentive state (Buechner et al., 2014) akin to alertness, if not also danger (also see Results). This is not surprising given that nature often signals potential threat by the use of red (e.g., some venomous spiders/snakes, blood loss, ruddy facial displays of aggression, the smoke haze of a catastrophic fire, etc.). By contrast, green, blue, and yellow may signal situationally appropriate foraging strategies which are undergirded by low/high motive states. For example, grasslands, forests, and coastal waters are resource rich and predominantly green or blue in color. Here a low motivation foraging strategy is appropriate with the psychobiological pay-offs of energy conservation, physiological recouperation, and pair-bonding. By contrast, harsh environments often rely on the “yellow sun” to germinate crops and/or bring migratory prey. Animals in harsh environments must therefore work hard to find and secure adequate resources. This is consistent with a foraging strategy characterized by high motivation and being future-focused. These two foraging strategies have been widely observed and given the names Brownian versus Lévy flight (de Jager et al., 2014; Sims et al., 2012). What’s more, the sun has a critical role in orchestrating the behaviors of predators in Lévy-appropriate harsh environments (Beumer et al., 2020; Helfman, 1986). For humans, the importance of this point lies in our ancestral ability to colonize harsh environments and our propensity for sun-focused worship/ceremonies/myths/songs/traditions which have an underlying narrative of hope. Seen in ancient religious beliefs (e.g., Egypt), and in traditional celebrations of the winter solstice, we may even suggest that great churches use sun-based motifs to augment a liturgy of hope. These motifs being architectural (e.g., dome of San Lorenzo, Turin), decorative (e.g., dome of Santa Maria Dei Miracoli, Saronno), or operationalized through the presence of yellow light—be it direct (e.g., candlelight), filtered through stained glass (e.g., St Patrick’s Cathedral, Melbourne), or reflected off gold ornamentation (e.g., St Mark’s Basilica, Venice).

Implications for Practice

BD practitioners must learn to be aware: (1) that their work may have its genesis in the hostility, not fecundity, of nature; (2) that color choices likely affect base-level psychophysiological attributes such as motivation and the perception of time, with any other effect being derivative and open to personal/cultural interpretation; (3) that inappropriate color juxtapositions may reduce the intended user experience; and (4) there is a recognized benefit to the judicious use of nonbiophilic colors and achromatic colors in healthcare settings (e.g., white promotes hygiene [Ulrich, 2001], while neutral toned counseling spaces may promote self-reflection [Sharp, 1991]).

With respect to design choices, BD practitioners may wish to consider a yellow color palette in settings such as oncology, rehabilitation, and mental health where hope is an important clinical adjunct. The basis for this being a need to maintain high levels of motivation among patients/carers/staff now and into the future. In extension of this argument, and reflecting on ancestral foraging strategies, BD practitioners may also wish to consider a palette of calming green/blue in emergency, pediatric (Park, 2009), maternity, and preoperative environments where patient/carer/staff arousal is likely to be high. Such a color palette may also have additional benefits including reducing movement in busy spaces, having users focus on the present at the expense of an uncertain future, and increasing the propensity for prosocial behaviors. Finally, red would appear to be a problematic color in healthcare settings best used when alerting people to something of immediate importance.

In sum, beyond the evocation of hope by a yellow cue, the current study sought to challenge implicit biophilic assumptions in light of evolutionary psychology and psychobiology. By doing so, practitioners were alerted to foundational aspects of mental processing. As a consequence, practitioners now have an opportunity to enhance biophilic outcomes and thus render further benefit to those engaging healthcare services.