Sensual Light? Subjective Dimensions of Ambient Illumination

Abstract

This work concerns the subjective impression of perceived illumination. The purpose of the study is to test attributes expressing qualitative experiences referring to ambient lighting that can be applied as descriptors. Seventy participants viewed an actual model room, with the fourth wall removed (viewing booth). Walls, floor, and ceiling were achromatic. Two achromatic cubes were placed inside the room: One was a reflectance increment to the walls, the other a decrement. The room was illuminated by two different light sources, Artificial Daylight (D65) or Tungsten Filament (F), the order of which was randomized across participants. The participants’ task was to evaluate ambient illumination for each light source. A semantic differential method was employed with 27 pairs of adjectives on 1 to 7 rating scales, categorized in three groups: characteristics of atmosphere, time, and cross-modal. Only the ratings of nine pairs of adjectives were not influenced by the type of illumination. The most differentiated couples under different illuminants were hot/cold and modern/old, but large differences also appeared with the following couples: hard/soft, technological/primitive, summery/wintry, warm/cool, sensual/frigid, natural/artificial, and hospitable/inhospitable. The hypothesis that there would be consistency among the subjects in evaluations of the characteristics tested and that these would be differently perceived under different illuminants was confirmed. The results show that it is possible to identify subjective perceived illumination as a phenomenon endowed with specific filling-in qualities and that as a perceptual experience it can be categorized, with implications for application in architecture and design.

Keywords

ambient lighting appearances connotative properties impressions light phenomena subjective experiences

Introduction

Illumination, or the luminous environment as subjectively perceived, embeds an array of environmental, expressive, atmospheric, aesthetic, and cross-modal qualities. One may experience, outdoors or indoors, a wet, cool, melancholic, and dusty light conveying a mood of anguish and grief; feel comfortable in a warm natural light or uncomfortable in a cold artificial light; and even be suddenly struck by a spring light on a late autumn day. An ambient light can be perceived as cozy or inhospitable, wet or dry as in tropical light, cool and silvery as in midnight moonlight, sharp as in direct sunlight, stagnant or flowing like the fluids in puddles or rivers, lambent and soft as with candle light, diffuse and flat as in an early morning without sun, and clear or dusky as in a polluted city. And this is so in whatever indoor or outdoor ambience, in any sort of artificial or natural light, and in whatever season. Because they are extremely variegated, the meaningful impressions conveyed by perceived illumination have captured the attention of designers of indoor and outdoor spaces (Boyce, 2003) interested in testing the influence of lighting to create specific comfortable or appealing atmospheres (Stokkermans, Yuexu, Murdoch, & Heynderinckx, 2015; Vogels, 2008), and a similar interest is shown by researchers in computer graphics and visualization (Knez, 1995; Flynn, 1992; Foley, van Dam, Feiner, & Hughes, 1997; McColl & Veitch, 2001).

Past studies on illumination have focused most often on the quality of illumination in relation to workplaces and task efficiency, and sometimes in relation to art appreciation (Loe, 2015). Yet, illumination quality is a crucial factor in generating particular atmospheres. Carbon and Deininger (2013), for instance, argued that the way in which we experience medieval art nowadays is quite different from how such artworks were originally meant to be viewed, and this is because of the difference in lighting conditions. From another perspective, Seuntiëns and Vogels (2008) analyzed light parameters such as brightness and temperature in combination with color, beam shaping, and dynamics to generate a cozy, activating, relaxing, and exciting atmosphere. Finally, the importance of lighting and its intrinsic qualities have received attention in art treatises and literature throughout the centuries (Baxandall, 1995; Cennini, 1398/2009; Da Vinci, 1804; Hogarth, 2002; Lomazzo, 1584; Schöne, 1979) and in literature on the architecture and design of lighting interfaces (Cuttle, 2003, 2010; Loe, Mansfield, & Rowlands, 1994; Madsen & Donn, 2006; Michel, 1996): A modern example is the Roden Crater by James Turrell, a large-scale artwork on light, illumination, and its modes of appearance during day and night and the changing seasons (http://rodencrater.com/).

Natural language, literary works, and geographic travel reports offer an astonishing repertoire of exact terminology to describe the multifarious appearances of ambient light as subjectively experienced by humans, such as Gemmea l’aria (gem-like is the air; Pascoli), E’ fosco l’aere (dim is the air; Foscolo), or harsh light (Woolf), oppressing slant of light (Dickinson). However, there is almost nothing comparable at hand in the scientific literature, not even at a classificatory or descriptive level. Science has extensively developed analysis of the objective, radiometric aspects of light such as radiance, luminance, and luminous environment, describing the objective illumination of the light field from the physical (natural) viewpoint and its properties (Fleming, Dror, & Adelson, 2003; Morgenstern, Geisler, & Murray, 2014; Morgenstern, Murray, & Geisler, 2010, 2011; Mury, Pont, & Koenderink, 2007, 2009; Olkkonen & Brainard, 2010; Pont & Koenderink, 2007; Xia, Pont, & Heynderinckx, 2014b); and its perception from a psychophysical viewpoint (Adelson & Bergen, 1991; Kartashova, Sekulovski, de Ridder, te Pas, & Pont, 2016; Koenderink, Pont, van Doorn, Kappers, & Todd, 2007; Maloney, 2002; Maloney, Gerhard, Boyaci, & Doerschner, 2010; Toscani, Gegenfurtner, & Doerschner, 2017; for a systematic review, from the inferential viewpoint, see Schirillo, 2013). Unfortunately, however, there has been no similar development in the analysis of perceived illumination in phenomenological terms, probably because the phenomenon as such is difficult to address and to identify using current approaches and methodologies, because it is characterized by a set of dimensions that apparently evade a quantitative explanation. The phenomenal percept, in fact, goes far beyond the input (physical, spatial-temporal energy patterns) and cannot be understood in terms of its representations. Only recently has the perception of environmental illumination from a subjective viewpoint been addressed in a few studies that discuss and present new methodologies to explore the phenomenon, in an attempt to reconstruct a trustable vocabulary for this type of experience (Pont, Mury, de Ridder, & Koenderink, 2009; Vogels, 2008). The analyses conducted to date concern pictorial and natural space, and the methods range from verbal judgments, through visual indicators (Pentland, 1982), to real gauge objects (Cuttle, 2003; Xia et al., 2014b; Xia, Pont, & Heynderickx, 2013, 2017) used to evaluate the subjective fitness of lighting to a real scene. The experiments have considered basic and correlated lighting dimensions such as intensity, diffuseness uniformity (Morgenstern et al., 2014; Stokkermans, Vogels, de Kort, & Heynderickx, 2017), and, with particular emphasis, direction (Koenderink & Pont, 2003; O’Shea, Agrawala, & Banks, 2010; Pentland, 1982; Xia, Pont, & Heynderinckx, 2014a, 2016). When these dimensions have been tested separately or simultaneously using a rough probe in a real scene (Xia et al., 2017), the observers were able to adjust for those lighting properties (although for diffuseness more coarsely, see also Toscani et al., 2017).

Despite a recent surge of interest in the perceptual experience of illumination, the discussion on its classification, the proper methodologies with which to analyze it, and the correct terminology to describe and to group lighting appearances are still at an early stage, most likely because of the multiple dimensions embedded in the phenomenon. A physical-mathematical language describing the input at the stimulus level is not suitable to describing the perceptual output, whose attributes are intrinsically meaningful. One has to assume a semantic relationship in perception and reconsider the nonarbitrary nature of natural language descriptions of the phenomena, which, however, do not correspond to physical properties of the world.

In the 1930s, however, in his seminal work, Katz (1935) offered a series of detailed descriptions of the subjective experience of illumination, as distinguished by both the light-emitting source and the illuminated object. In awareness, lighting (Erleuchtung, in Katz)—or, in a better English translation, experienced illumination—appears to be a primary impression even before the color impression, and it is located in the visual empty space between ourselves and the objects (Katz, 1935). For example, in the case of a space in light and shadow behind or within a box, the observer may have the impression of two spaces, one placed in front of the other. The space appears as more or less illuminated or filled with strong or weak illumination (Katz, 1935). Moreover, it appears similar to volume colors: at twilight, for example, when parts of the visual field clearly appear to be put in shadow. Volume colors, in fact, besides filling a 3-D space, are at their best when genuinely transparent. Hence, perceived illumination, besides being a phenomenal datum, seems to behave as a creator/destroyer of space, also empty space (Katz, 1935; Koffka, 1935; Michel, 1996).

The qualitative appearance of perceived illumination raises the question of how to categorize it, that is, whether the phenomenon can or cannot be classified under any of the accepted scientific categories (in this case, e.g., illumination in relation to lightness) or, vice versa, if it can be identified and characterized per se according to specific properties. In vision science, the issue has been addressed by considering perceived illumination in relation to different aspects of light perception, such as color constancy and perceived surface lightness and brightness (Boyce, 2003; Brainard, 1998; Gilchrist, 2006; Zavagno & Massironi, 1997) or the mutual dependence or independence of lightness and illumination (Bergström, 1994, 2004; Gilchrist, 1994; Gilchrist, Delman, & Jacobsen, 1983; Katz, 1935; Kingdom, 2011; Koffka, 1935; Zavagno & Daneyko, 2008; Zavagno, Daneyko, & Sakurai, 2011; Zavagno & Massironi, 2006). The studies have been guided by different hypotheses and reached different conclusions (see Gilchrist, 2006, Chap. 8; Kingdom, 2011): essentially, either discharging or eliminating the phenomenon (Helmholtz, 1866/1962; Helson, 1943; Jaensch, 1919; Wallach, 1976) or, vice versa, viewing the perception of illumination to be as immediate as object color perception (Karpinska, 1910; Katz, 1935; Koffka, 1935; MacLeod, 1932; Schumann, 1920). In the latter case, the phenomenon is considered independent of color and detachable from other perceptual dimensions, although it requires specific training in observation and a specific methodology to be verified and explained. That said, the literature specifically devoted to the perception of illumination is still scant compared with the extensive literature on color perception (both chromatic and achromatic). Nor is there any accredited terminology to refer to lighting qualities because of their subjective and apparently imprecise categorization (see Mausfeld, 2013). As Pont (2013) observes, there is no standardized terminology for the luminosity framework, and a complete review of terminology used in different fields would be beyond the scope of any experimental study. Pont et al. analyzed the luminosity framework using an appearance-based approach. They started by asking nonprofessionals (students) to produce informal descriptions of light that would provide insights into phenomenological aspects of light qualities as they are experienced in ecologically valid conditions. The descriptions, scored on a Boolean table, resulted in two large clusters in the data: One cluster contained mainly terms that describe the luminosity framework; the other contained mainly terms that describe the lighting atmosphere (Vogels, 2008); the former group could be further divided into three groups describing the primary source, the spatial structure of the luminous environment or shape of a beam, and its appearance. As Pont observes, in the scoring of the Boolean table, there may be the risk of subjective interpretations, although the study provides a sort of provisional mindmap of semantic clusters for words describing light.

The Study

The purpose of this study is to test some attributes expressing subjective experiences of perceived illumination as space-filling qualities that may be applied as descriptors. The goal is to provide a set of terms that, although not exhaustive, can be employed to frame and describe in a coherent and reliable way experiences that refer specifically to ambient illumination. Along with this goal, we also want to test for possible phenomenal dimensions under which umbrella terms may group as traits of specific dimensions. In other words, the purpose is to define a proper vocabulary that can be unambiguously employed to describe a set of different appearances that may characterize ambient illumination.

Studies addressing the attributes of visual experiences have been conducted relatively to material appearances of objects’ perceptual surfaces (Kingdom, 2008), such as being rough, dry, malleable, silky, and so on (Fleming, 2014; Mausfeld, 2013), or to motion perception (Heider & Simmel, 1944; Scholl & Tremoulet, 2000). Indeed, perceived illumination has sometimes been likened to or confused with the perceived material properties of objects’ surfaces (Motoyoshi, Nishida, Sharan, & Adelson, 2007). Vice versa, we are interested in the qualities of perceived illumination per se from a purely phenomenological viewpoint, without concerns about causes and conditions of their arising from a psychophysical or a neurophysiological viewpoint (Albertazzi, 2015). Specifically, we are interested in verifying whether in the perceived illumination of a 3-D empty space there are connotative invariants allowing a perceiver to identify, for example, a winter- or spring-like lighting, notwithstanding the complexity of the components that might be involved in such a categorization, or to experience emotional characteristics with affordance valence (such as lighting being perceived as annoying, cozy, eerie, sensual; Knez, 1995, 2001). Finally, we also want to verify the presence of cross-modal associations (those relative to softness, humidity, flux, weight, acidity) extending far beyond purely visual attributes (Köhler, 1947). As to this latter point, we are particularly interested in testing for cross-modal associations between perceived illumination and tactile qualities, as observed by Katz (1935).

Regarding the number and the kind of characteristics to be tested, some studies on word usage for descriptors in arts have recently appeared (Augustin, Carbon, & Wagemans, 2012; Augustin, Wagemans, & Carbon, 2012; Istok et al., 2009; Jacobsen, Buchta, Kohler, & Schröger, 2004). Besides the different focus (we were not considering art, nor the aspects of illumination in art), in our study, we did not start by submitting a questionnaire of terms to the participants to extract those most used in describing the field, and we did not start from a collection of descriptions made by laypersons. Also, we were not looking for universal and exhaustive descriptors, being aware of the ambiguities that may concern different conceptualizations underlying the vocabulary of different languages, and the shifts of language use over the years even for a single language. We started, instead, by considering a relatively short list of characteristics according to the three dimensions that we wanted to test, that is, terms related to time (e.g., seasonal, common in most languages, such as summery and wintry), terms with an affective value or referring to affordances, or other tertiary qualities (Köhler, 1969), frequent in design studies, such as comfortable and modern), and terms that we hypothesized might show a cross-modal dimension of perceived light (such as hard and soft), following indications given by Katz, as mentioned earlier. Among the dimensions considered, we avoided, for example, using terms such as beautiful because they potentially embed a large meaning ambiguity and correspond to a highly subjective experience. Briefly, the terms were chosen accordingly to (a) a specific categorial choice, (b) a hypothesis that we wanted to verify, and (c) a specific aim, that is, to conduct a visual experiment on perceived light in which terms were not abstractedly considered in reference to illumination in general, but applied as possible descriptors of illumination qualities directly experienced by observers.

Illumination is a spatial experience, and it can be experienced only in relation to an environment, be this actual or pictorial (Zavagno, 2007). This implies that illumination may be modulated in its appearance (intensity, color, clarity, etc.) not only by the type of light source that provides for ambient illumination (or that is implied in a pictorial representation) but also by the same objects that modulate the appearance of space. Hence, to address our research goals, we decided to create an actual miniature room illuminated by two different light sources. The environment was illuminated from above. It consisted of a gray floor and three gray walls and included two cubes that differed by shade of gray, one being dark, the other light. The two cubes served to counterbalance brightness effects (e.g., edge crispening, brightness diffusion, ambient brightness assimilation) of brighter/darker illuminants on lighter/darker surfaces. The purpose of the setup was to provide sufficient visual information to appreciate the appearance of illumination in a nonoverwhelming visual environment. In other words, we wanted our participants to focus on the visual characteristics of illumination in a neutral room with sufficient spatial articulation, but without focusing on the room itself. The guiding hypothesis of the study was that it is possible to identify perceived illumination as a specific phenomenon, endowed with filling-in qualities that can be categorized according to a list of attributes; and finally, that under different illuminants, the modes of appearances of ambient illumination are differently perceived.

Participants

Seventy participants volunteered for the experiment: 38 women and 32 men (age range: 19–69; mean age = 28 years; SD = 12.4; median = 22 years). All participants were recruited by e-mail from students in the Departments of Humanities, Engineering, and Psychology and Cognitive Sciences of the University of Trento, Italy. Some colleagues at the same Departments acted as subjects as well. The address list of the students was provided by the student office. We first sent an e-mail asking the students to take part in the experiment. We did not ask for persons with professional experience in color and light, such as light designers (although a few subjects had received artistic training at high school, as recorded by the instructor), and we did not use any questionnaire. The only exclusion criterion was self-reported visual impairment. All the participants signed an informed consent form. The experiments reported here complied with the ethical guidelines of the University of Trento.

Materials

The experiment was conducted with a Viewing Booth VeriVide Colour Assessment Cabinet CAC 60-5 (henceforth, the viewing booth will be referred to as the room), equipped with five different types of light sources. For the experiment, we used two illuminants: F Tungsten Filament Lighting (approximate color temperature of 2800 K, approximating CIE Illuminant A) and D65 Artificial Daylight (correlated color temperature of 6500 K). The two illuminants (henceforth F and D65) were alternated before each new test. The measured values for F were 2380 K (color temperature), and 815 lx (illuminance) and for D65 were 4970 K, and 1970 lx. Measurements taken in a single point inside the room—by placing the instrument in the center of the horizontal plane with the probe facing upward, perpendicular to the light—were conducted to allow for experimental repeatability. The measuring instruments were a Gossen Colormaster 3F color temperature meter and a UNI-T UT382 USB luxmeter. The room’s internal viewing area size were L 680 × W 495 × H 360 (mm), internal finishes NCS S5502-G. The room included 2 cubes made of forex (side = 90 mm), coated with two different shades of gray, one light (C1 = NCS S 1000-N) and one dark (C2 = NCS S 8000-N), so that C1 was a reflectance increment to the room’s walls and C2 a decrement. C1 and C2 were positioned as shown in Figure 1. The pavement of the room was a sheet of gray paper (NCS S 2005-R60B).

Figure 1.

The room with illuminant D65 and the rating device employed.

The experiment was performed using the semantic differential on a rating scale of adjectives (Osgood, 1956). The adjectives were presented in couples and randomized. A rating device was employed (see Figure 1), in which a sliding cursor indicated the participants’ rating choices on the scales. It was made clear to the participants that the left side of the scale was anchored to the first adjective and the right side to the second adjective for each pair of adjectives. A red dot indicated the middle of the rating device, and it was explained to participants that central values or the middle point indicated no preference for either adjective in relation to perceived illumination. On the rear part of the continuous scale (going from a minimum to a maximum), and invisible to the participants, the device was divided into seven steps, according to which the evaluations were recorded. As shown in the right panel of Figure 1, the rating device was equipped with a graphic representation of intensity: The central dot indicated a flection from which two wings departed, growing thicker as they approached respectively the left and right ends. How to use the scale was thoroughly explained to participants.

The 27 adjectives pairs were Italian words pertaining to three main categories (the second of which included several dimensions that refer to atmosphere qualities and tertiary qualities, Köhler, 1969):

Pertaining to time, such as seasonal or day and night characteristics: primaverile/autunnale (vernal/autumnal), estiva/invernale (summery/wintry), diurna/notturna (diurnal/nocturnal);

With affective, aesthetic, and affordance valence (henceforth atmosphere valence): sensuale/frigida (sensual/frigid), naturale/artificiale (natural/artificial), accogliente/inospitale (hospitable/inhospitable), moderna/vecchia (modern/old), confortevole/fastidiosa (comfortable/annoying), tecnologica/primitiva (technological/primitive), pulita/sporca (clean/dirty), languida/energica (languid/energetic), timida/esuberante (timid/exuberant), allegra/triste (happy/sad), gioiosa/lugubre (joyful/gloomy), raffinata/squallida (refined/squalid);

Referring to cross-modal dimensions: asciutta/umida (dry/damp), dolce/acida (sweet/sour), fluente/stagnante (flowing/stagnant), dura/molle (hard/soft), calda/fredda (hot/cold), tiepida/fresca (warm/cool), appiccicosa/secca (sticky/unsticky), squillante/spenta (shrill/muted), limpida/fosca (limpid/dim), vivace/smorta (vivacious/dull), intensa/debole (intense/weak), diffusa/tagliente (diffused/sharp).

Procedure

The experiment was performed in the LabExP of the Department of Humanities of Trento University. The walls of this lab are coated with gray NCS S 5502-G. The ambient illumination was controlled by a colorimetro Gossen, Colormaster 3F, and by a Lùxmetro UNI-T, UT382 USB. A halogen lamp (230 V 30 W, 3000 K) was placed on the table to the right of the miniaturized room, and it was used by the experimenter to read the instructions and record the choices of the participants on a paper form. The light beam of this additional lamp did neither illuminate the booth nor the observer’s eyes.

Participants viewed the miniature room binocularly from a distance of 70 cm. For their subjective judgments, they were told not to rely on past experience or to make inferences, vice versa to evaluate the light impression as such after careful observation of the phenomenon. No immediate answer was required from the participants. When seated, they were read the following instructions:

Your task is to evaluate some dimensions, such as dry/damp, comfortable/annoying, etc. in relation to two conditions of ambient illumination that you will experience separately looking at a miniaturized room with two cubes inside it. Pairs of adjectives will be presented to you, and for each pair you will evaluate whether the ambient illumination you see is more similar to the first term (for example dry) or to the second term (for example damp) by sliding the pointer on the scale of the rating device placed in front of you. The closer you move the pointer to the far left or to the far right of the scale, the more you think that the first term (left) or the second term (right) is a good descriptor of the ambient illumination you are looking at; the closer you position the pointer to the center, the less the fit of the terms with regards to how you experience the ambient illumination you are looking at. If you think that the two terms have nothing to do with your experience, then you should position the pointer right on the red dot.

After the instructions were given, participants were asked if they had any questions concerning the rating device. If no questions were asked, the researcher pointed to the graphical representation of rating intensities on the scale, making it clear that the closer to the red dot the less intense was the rating for either one of the adjectives, with the red dot indicating that neither of the adjectives was meaningful in reference to the illumination that they saw. They were also informed that their task was not to rate how illumination appeared on the cubes, but to consider how the illumination in the miniaturized room appeared in general.

Statistical Methods

On each of the qualities considered (i.e., the 27 pairs of adjectives), a Student’s t test for paired data was performed to compare the mean scores given by the subjects participating in the experiment under the two different light sources. A principal component analysis (PCA) was performed on the correlation matrix between the adjectives after having applied the doubling procedure described by Greenacre (2007). The idea behind doubling is to redefine the scale of each of the 27 qualities examined as a pair of complementary scales. Statistical analyses were performed employing R (2016).

Results

Figure 2 shows the mean scores given to each of the 27 pairs of adjectives under the two illuminants (F and D65). Under the first, ambient illumination received high evaluations for diffused, hot, warm, hospitable, comfortable, and sweet and medium evaluations for old, languid, joyful, refined, sensual, and soft. Under illuminant D65, ambient illumination received high evaluations for artificial, modern, technological, clean, wintry, cold, hard, limpid, frigid, unsticky, dry and medium evaluations for intense and cool.

Figure 2.

Mean scores given to each of the 27 pairs of adjectives under the two illuminants (circles: D65; squares: F). The pairs are sorted in descending order by effect size (E.S.).

A direct comparison of the mean values employing t tests for paired data showed significant results (at the 5% significance level) for the first 22 pairs of adjectives displayed in Figure 2. In the supplementary material, there is a table giving descriptive statistics (means and standard deviations) as well as the results of the t tests with the corresponding p values. For 9 of the 22 pairs of adjectives, the p values were smaller than 10⁻⁹, and for another 6, the p values were smaller than 10⁻⁵. If one adopts the highly penalizing Bonferroni correction, only 4 pairs of adjectives become no longer significant (they are in the positions from 19 to 22 in Figure 2).

The pairs of adjectives most bipolarized by the two ambient illuminations were hot/cold and modern/old; their differences were 3.30 and 3.14, respectively. Because the scale adopted ranges between 1 and 7, a difference greater than 3 points can be considered a large effect (over 50% of the admissible range). The effect sizes calculated according to Cohen (1988) were, respectively, 1.40 and 1.37, that is, very large. Three other pairs of adjectives showed mean differences greater than 2.5; these were hard/soft, technological/primitive, and natural/artificial, with effect sizes 1.12, 1.07, and 0.92, respectively. Four other pairs had mean differences greater than 2: warm/cool, sensual/frigid, summery/wintry, and hospitable/inhospitable, with effect sizes ranging between 0.86 and 0.95. All these effect sizes can be considered large according to Cohen. Seven pairs showed effect sizes between 0.5 and 0.8 (i.e., between medium and large).

For all these 16 pairs, the p values were well below the significance level corrected according to Bonferroni.

These pairs are set out in Figure 2, where they are sorted by effect size in decreasing order. Only the last five pairs displayed in Figure 2 produced ratings that did not differ much under the two illuminants (effect sizes ranging between 0.03 and 0.20 and with uncorrected p values higher than .05). Four other pairs showed effect sizes ranging between 0.25 and 0.35, but with Bonferroni corrected p values higher than .05.

In general, the ambient illumination resulting from illuminant D65 determined greater polarization in the ratings of adjective pairs, with a distance from the center of the scale exceeding 2 points for the adjectives artificial, modern, technological, and clean, and a distance of 1.94 for wintry. The ambient illumination determined by illuminant F, instead, engendered somewhat weaker polarization in which the stronger effects were found for the adjectives diffused, hot, comfortable, warm, and hospitable, with mean distances from the center between 1.4 and 1.5 points.

To analyze the semantic structure across both lighting conditions, a PCA was conducted on the correlation matrix of the 27 scores given by the participants. The first four components explained 60.9% of the variance (the first 32.5%, the second 16.2%, the third 7.3%, the fourth 4.8%). Figure 3 shows the distribution of adjective pairs that have a correlation coefficient with the first or the second (unrotated) component greater than .6 in absolute value; the terms of each pair are represented on opposite sides with respect to the origin of the axes. A similar figure representing the distribution of all the 27 adjective pairs, as well as a table giving the correlations between the adjectives and the first four principal components can be found in the supplementary material.

Figure 3.

Adjective pairs that showed a correlation greater than .6 (in absolute value) with the first or with the second principal component. A dotted line connects the two adjectives of a pair. The first six characters of each adjective are shown.

The first principal component (horizontal axis in Figure 3) is characterized by the pairs hard/soft, hot/cold, sensual/frigid, hospitable/inhospitable, modern/old, natural/artificial, sweet/sour, which showed a correlation higher than .7 (in absolute value). On the other hand, only two pairs (vivacious/dull, happy/sad) showed a correlation higher than .7 (in absolute value) with the second principal component (vertical axis in Figure 3).

To evaluate if the components extracted could be considered consistent descriptors of ambient lighting, for each subject the scores on the principal components (PCA scores) were calculated under the two lighting conditions. Figure 4 (left panel) shows these scores relative to the first two principal components. It is evident that, on the first principal component, the scores are well separated, with 62 positive scores (out of 70) given under the illuminant F and 59 negative scores (out of 70) given under the illuminant D65. On the other hand, with regard to the second principal component, the scores do not appear separated (with 37 positive scores given under the illuminant F and 38 negative scores given under the illuminant D65); similar results were found for all the remaining principal components.

Figure 4.

Left panel: scatterplot of the scores on the first two principal components (circles for the illuminant D65; squares for the illuminant F). Right panel: density plot of the scores on the first principal component separately for the two illuminants (dashed lines: D65; dotted lines: F).

For all the 27 principal components extracted (which reproduced 100% of the variability of the original scores), the PCA scores under the two illuminants were calculated and compared by employing the Student’s t test for paired data. The detailed results of this comparison are reported in the supplementary material. The difference between the mean PCA scores was significant only for the first principal component (with a p value below 10⁻¹⁸); that is, there were 65 negative differences (F – D65) and only 5 positives. The p value of the comparison relative to the third principal component was .041, which can be considered not significant on applying the Bonferroni correction. All the remaining p values were higher than .17.

Therefore, the first principal component appears to capture the difference due to ambient illumination, particularly by cross-modal and atmosphere characteristics: We can term it the cross-modal expressive value of perceived illumination. This is particularly evident from the right panel of Figure 4, where the density estimate of the distribution of the PCA scores of the first principal component was evaluated separately for the two illuminants. On the other hand, 10 of the 11 adjective pairs that showed a correlation with the first principal component higher than .6 (in absolute value) are in the first 10 positions displayed in Figure 2.

General Discussion

Our study analyzed the subjective impressions of perceived illumination relative to a range of connotative characteristics of the phenomenon grouped into three macrocategories (i.e., time, atmosphere valence, and cross-modal). Differently from other studies, we did not work on pictorial space, but on actual space, albeit within a miniaturized setting. Similarly, differently from other studies, we did not make any comparison between the physical dimensions of lighting and the perceived illumination (Kartashova et al., 2016; Koenderink et al., 2007; Xia et al., 2014a) because the topic of our study is the experience of illumination solely from a subjective and qualitative viewpoint. Contrary to other works developed in the design research field, we tested neither color lighting and temporal dynamics, nor beam angles, and we did not make use of a questionnaire (Seuntiëns & Vogels, 2008; Vogels, 2008; Vogels, de Vries, & van Erp, 2008; Wang et al., 2014). Specifically, regarding the dimensions tested by us and by the Vogels’ group, although a certain similarity can be detected, there are several differences. First, we tested three different categories (time-related, atmosphere-related, and cross-modal), which do not overlap with the research aim and the consequent choice of the four dimensions tested by the Vogels’ group. In fact, with regard to Vogels’ list of categories (coziness, liveliness, detachedness, and tenseness), only coziness and liveness were adjectives present also in our study. Second, we tested a greater number of subjects, and without any professional expertise in the field (see also Kuijsters, Redi, de Ruyter, Seuntiëns, & Heynderickx, 2014), and a greater number of terms referred to lighting characteristics. Specifically, compared with the list of adjectives (38) tested in Vogels (2008), we tested (27) pairs of contraries, several of which (12) referred to cross-modal characteristics of the percept. Our interest, in fact, was more general, that is not restricted to lighting design issues and therefore interested in a wider range of perceptual experiences. As said, Vogels’ model aimed at defining a tool able to qualify a certain number of experiences of the affective-usability type, such as coziness, may show a certain similarity to our study. However, her aim is to understand the variables underlying the different experiences; ours is to define the underlying dimensions of perceived illumination by means of a linguistic tool. Specifically, as said, we neither consider any physical dimensions of lighting nor make any comparison between subjective and objective dimensions to show how people may infer (physical) light itself (Schirillo, 2013). Finally, we conducted our experiment in a miniaturized space (the viewing booth), that is, neither in a real scene nor in a pictorial space.

The results showed that it is possible to identify illumination as a phenomenological presence in our visual space endowed with specific filling-in qualities relative to its modes of appearances and that it can be categorized. The hypothesis that there would be consistency among the subjects in their evaluations of the characteristics, and that these would be differently perceived under different illuminants, was confirmed.

Regarding the influence of the different illuminants on the perceived characteristics, the effect is verifiable in most of the attributes (18) of the three macrocategories, and it is particularly visible in 9 of them (hot/cold, modern/old, hard/soft, technological/primitive, summery/wintry, warm/cool, sensual/frigid, natural/artificial, and hospitable/inhospitable). PCA confirmed these findings. Hence, in the majority of cases, the attributes denoted by adjective pairs were evaluated by participants as genuine polarizable expressions of characteristics peculiar to the phenomenon. Specifically, under F lighting, ambient illumination was definitely perceived not only as diffused, hot, warm, hospitable, comfortable, and sweet but also somewhat old, languid, joyful, refined, sensual, and soft. Under illuminant D65, instead, ambient illumination was definitely perceived not only as artificial, modern, technological, clean, wintry, cold, hard, limpid, frigid, unsticky, and dry but also somewhat intense and cool.

The pair of adjectives most bipolarized for the two illuminants was hot/cold, which are attributes that also describe color experiences (Katz, 1935). This, however, is not the only cross-modal association that characterizes perceived illumination; other terms are in fact related to tactile perceptions, such as warm/cool, hard/soft, dry/damp, sticky/unsticky, also observed by Katz (1935) for surface color, and taste perception with the pair sweet/sour.

As one would expect, dimensions such as the diffuseness and the intensity of lighting, considered also in other studies (Morgenstern et al., 2010, 2011, 2014), are also connotative qualities of ambient lighting; diffuseness in particular appears to be more characterized with illuminant F, inducing a sensual dimension to ambient illumination.

As to the affective/affordance (atmosphere) attributes, besides the consistency of hospitable/inhospitable, classically analyzed in design research, sometimes with slightly different attributes such as cozy, annoying, eerie, sensual (Knez, 1995, 2001), an interesting result is shown by the sensual/frigid couple, which is highly significant and with a large effect size.

As to the time-related attributes, while the impressions of summery/wintry are well characterized, attributes such as vernal/autumnal and diurnal/nocturnal are not. The former result could depend on the less invariant characteristics of actual intermediate seasons in our latitude, especially in recent decades. However, the pairs hot/cold and warm/cool might be representative of the difference between cold and warm seasons (such as winter and summer), and intermediate seasons (such as spring and autumn). Vice versa, no significant results are provided for the couple diurnal and nocturnal; these can be considered significant dimensions in design studies, where atmosphere characteristics of lighting, such as hospitable/inhospitable, and so forth, are related by a combination of artificial lighting and daylight naturally entering the room (Seuntiëns & Vogels, 2008).

Contrary to our expectations, some tertiary features, such as refined/squalid and vivacious/dull, and the cross-modal features related to liquids—flowing/stagnant—were not considered to be visible features of the ambient illuminations that we employed. This result may be due to our setup with the viewing booth, which may be more suitable for identifying more static—though complex—features such as sticky/unsticky and dry/damp. Whether the aforementioned pairs are actually irrelevant as descriptors of qualities related to ambient illumination should be tested with other illuminants, other lighting conditions (e.g., light coming from a corner), and also with the observer immersed in the environment, may this be actual or experienced with immersive virtual reality technology.

Only a few dimensions were polarized for one illuminant but not for the other (i.e., for the other illuminant, mean rating approximated 4). For example, the limpid/dim pair was highly polarized with illuminant D65 but was not relevant with illuminant F; vice versa languid/energetic was polarized with F but not with D65. This indicates that such dimensions are descriptors that relate to a particular condition of illumination and may also be dependent on the perceived brightness of the environment in more general terms. More studies are required to test this hypothesis.

As to the relationship between perceiving and naming the characteristics of the phenomenon of lighting, the absence of a correspondence between the semantic and the perceptual dimensions cannot be maintained: The agreement by the (Italian speaking) 70 participants on the attributes of perceived dimensions of light was consistent. As said, only in a few cases (i.e., for few adjectives) was an option close to the neutral value chosen on average by the participants, and generally not with both illuminants. In other words, specific qualitative phenomena related to lighting terms (at least as concerns the Italian language) prove to be trustable categories of classification for subjective experiences (see Albertazzi & Da Pos, 2016). In the future, other studies may repeat the experiment with subjects speaking a very different language, to test the appropriateness of their linguistic categories to the different appearances of perceived illumination.

Even more interesting would be a new partial test focusing on the cross-modal attributes verifying the association with real hard/soft or dry/damp items, be they surfaces, objects, or liquids (Murari et al., 2015). Further studies could also test the same (and or other) characteristics in synaesthetes.

It would be also interesting to verify whether some connotative qualities of colors responsible for the advancing/retreating effect (Chen & Lin, 2015; Einthoven, 1885; Katz, 1935; Vos, 2008) or the expansion/contraction effect (Katz, 1935) in surfaces can be subjectively perceived also in relation to lighting space.

Other improvements in the design may concern the division into a larger number of intervals for the evaluations. In fact, comparably large variations in slider position could still fall within the same interval, while rather small variations could fall within two different intervals. To render the results more generalizable, one could also balance the physical dimensions of the illuminants to be chosen and vary their intensities accordingly. This would make it possible to test the effect of intensity on the same categories proposed in this study. However, such intensity balancing would most likely affect also the color temperature of the two illuminants, making it impossible to test for a pure intensity effect on participants’ responses.

Finally, on the basis of recent findings on the similarity between human and nonhuman behavior relatively to contextual perceptions, it would be very interesting to test, by appropriate methods, some qualities of lighting in the animal realm.

Supplemental Material

Supplemental material for Sensual Light? Subjective Dimensions of Ambient Illumination

Supplemental material for Sensual Light? Subjective Dimensions of Ambient Illumination by Liliana Albertazzi, Luisa Canal, Paolo Chisté, Rocco Micciolo and Daniele Zavagno in Perception

Footnotes

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: The study was conducted within a project on Light and Colour supported by the Academic Senate of the University of Trento.

Supplementary Material

Supplementary material for this article is available online.

References

Adelson

E. H.

Bergen

G. R.

(1991). The plenoptic function and the elements of early vision. In Landy

Movshon

J. A.

(Eds.), Computational models of visual processing (pp. 3–20). Cambridge, MA: MIT Press.

Albertazzi

(2015). A science of qualities. Biological Theory, 10, 188. doi:10.1007/s13752-015-0213-3

Albertazzi

Da Pos

(2016). Color names, stimulus color, and their subjective links. Color Research and Application, 42, 89–101. doi:10.1002/col.22034

Augustin

M. D.

Carbon

C.-C.

Wagemans

(2012). Artful terms: A study on aesthetic word usage for visual arts vs. film and music. i-Perception, 3, 319–337. doi:10.1068/i0511aap

Augustin

M. D.

Wagemans

Carbon

C.-C.

(2012). All is beautiful? Generality vs. specificity of word usage in visual aesthetics. Acta Psychologica, 139, 187–201. doi:10.1016/j.actpsy.2011.10.004

Baxandall

(1995). Shadows and enlightenment. New Haven, CT: Yale University Press.

Bergström

S. S.

(1994). Color constancy: Arguments for a vector model for the perception of illumination, color, and depth. In Gilchrist

(Ed.), Lightness, brightness and transparency (pp. 257–286). Hillsdale, NJ: Lawrence Erlbaum Associates.

Bergström

S. S.

(2004). The AMBEGUJAS phenomenon and colour constancy. Perception, 33, 831–835.

Boyce

P. R.

(2003). Human factors in lightning (2nd ed.). Boca Raton, FL: CRC Press.

10.

Brainard

D. H.

(1998). Color constancy in the nearly natural image. 2. Achromatic loci. Journal of the Optical Society of America. A, Optics, Image Science, and Vision, 15, 307–325.

11.

Carbon

C.-C.

Deininger

(2013). Golden perception: Simulating perceptual habits of the past. i-Perception, 4, 468–476. doi:10.1068/i0605

12.

Cennini

(1398/2009). Il libro dell’arte [The Book of Art]. Venezia, Italy: Neri Pozza.

13.

Chen

Lin

(2015, November 2). Quantitative assessment of the advancing/receding and the expansion/constriction effects of colours. AIC Colour 05 – 10th Congress of the International Colour Association. The Journal of Neuroscience, 30, 14964–14971.

14.

Cohen

(1988). Statistical power analysis for the behavioral sciences. London, England: Routledge.

15.

Cuttle

(2003). Lightning by design. Amsterdam, the Netherlands: Elsevier.

16.

Cuttle

(2010). Towards the third stage of the lightning profession. Lightning Research and Technology, 42, 73–93. doi:10.1177/1477153509104013

17.

Da Vinci

(1804). Trattato della pittura di Lionardo Da Vinci [Painting treatise by Leonardo Da Vinci]. Milano, Italy: Dalla Società Tipografica de' Classici Italiani, Contrada di S. Margherita, n. 1118.

18.

Einthoven

(1885). Stereoscopie door kleurverschil (PhD thesis). Utrecht University, the Netherlands.

19.

Fleming

R. W.

(2014). Visual perception of materials and their properties. Vision Research, 94, 62–75.

20.

Fleming

R. W.

Dror

R. O.

Adelson

E. H.

(2003). Real world illumination and the perception of surface reflectance properties. Journal of Vision, 3, 347–368.

21.

Flynn

J. E.

(1992). Lighting-design decisions as interventions in human visual space. In Nasar

J. L.

(Ed.), Environmental aesthetics: Theory, research and applications (pp. 156–170). New York, NY: Cambridge University Press.

22.

Foley

J. D.

van Dam

Feiner

S. K.

Hughes

J. F.

(1997). Computer graphics, principles and practices (2nd ed.). Boston, MA: Addison-Wesley Publishing Company.

23.

Gilchrist

(1994). Introduction: Absolute versus relative theories of lightness perception. In Gilchrist

(Ed.), Lightness, brightness and transparency (pp. 1–34). Hillsdale, NJ: Lawrence Erlbaum Associates.

24.

Gilchrist

(2006). Seeing black and white. Oxford, England: Oxford University Press.

25.

Gilchrist

Delman

Jacobsen

(1983). The classification and integration of edges as critical to the perception of reflectance and illumination. Perception & Psychophysics, 33, 425–436.

26.

Greenacre

(2007). Correspondence analysis in practice (2nd ed.). Boca Raton, FL: Chapman & Hall/CRC Press.

27.

Heider

Simmel

(1944). An experimental study of apparent behaviour. The American Journal of Psychology, 57, 243–259.

28.

Helmholtz

H. von.

(1866/1962). Handbook der Physiologischen Optic [Handbook of physiological optics]. Hamburg: Voss [En. tr. 1962; New York, NY: Dover].

29.

Helson

(1943). Some factors and implications of color constancy. Journal of the Optical Society of America A, 33, 555–567.

30.

Hogarth

(2002). Dynamic light and shade. New York, NY: Watson-Guptill Publications.

31.

Istok

Brattico

Jacobsen

Krohn

Muller

Tervaniemi

(2009). Aesthetic response to music: A questionnaire study. Musicae Scientiae, 13, 183–206. doi:10.1177/102986490901300201

32.

Jacobsen

Buchta

Kohler

Schröger

(2004). The primacy of beauty in judging the aesthetics of objects. Psychological Reports, 94, 1253–1260. doi:10.2466/pr0.94.3c.1253-1260

33.

Jaensch

(1919). Über Grundfragen der Farbenpsychologie [On basic questions concerning the psychology of color]. Zeitschrift für Psychologie, 83, 257–265.

34.

Karpinska

(1910). Experimentelle Beiträge zur Analyse der Tiefenwahrnehmung [Experimental contribution to the analysis of depth perception]. Zeitschrift für Psychologie, 57, 1–89.

35.

Kartashova

Sekulovski

de Ridder

te Pas

S. F.

Pont

S. C.

(2016). The global structure of the visual light field and its relation to the physical light field. Journal of Vision, 16, 9. doi:10.1167/16.10.9

36.

Katz

(1935). The world of color. London, England: Kegan Paul.

37.

Kingdom

F. A. A.

(2008). Perceiving light versus material. Vision Research, 48, 2090–2105. doi:10.1016/j.visres.2008.03.020

38.

Kingdom

F. A. A.

(2011). Lightness, brightness and transparency: A quarter century of new ideas, captivating demonstrations and unrelenting controversy. Vision Research, 51, 652–673. doi:10.1016/j.visres.2010.09.012

39.

Knez

(1995). Effects of indoor lighting on mood and cognition. Journal of Environmental Psychology, 15, 39–51.

40.

Knez

(2001). Effects of noise, heat and indoor lighting on cognitive performance and self-reported affect. Journal of Environmental Psychology, 21, 291–299. doi:10.1006/jevp.2001.0222

41.

Koenderink

J. J.

Pont

S. C.

(2003). Irradiation direction from texture. Journal of the Optical Society of America A, 20, 1875–1882.

42.

Koenderink

J. J.

Pont

S. C.

van Doorn

A. J.

Kappers

A. M. L.

Todd

J. T.

(2007). The visual light field. Perception, 36, 1595–1610. doi:10.1068/p5672

43.

Koffka

(1935). Principles of Gestalt psychology. New York, NY: Harcourt, Brace, and World.

44.

Köhler

(1947). Gestalt psychology: An introduction to new concepts in modern psychology. New York, NY: Liveright.

45.

Köhler

(1969). The task of Gestalt psychology. Princeton, NJ: Princeton University Press.

46.

Kuijsters

Redi

de Ruyter

Seuntiëns

Heynderickx

(2014). Affective ambiences created with lighting for older people. Lighting Research Technology, 47, 1–17. doi:10.1177/1477153514560423

47.

Loe

D. L.

(2015). Light, vision and illumination: The interaction revisited. Lighting Research and Technology, 48, 176–189. doi:10.1177/1477153515572240

48.

Loe

D. L.

Mansfield

K. P.

Rowlands

(1994). Appearance of lit environment and its relevance in lighting design: Experimental study. Lighting Research and Technology, 26, 119–133.

49.

Lomazzo

G. P.

(1584). Trattato della pittura, scultura et architettura [Treatise on painting, sculpture and architecture]. Milano, Italy: Paolo Gottardo Pontio, Stampatore Regio.

50.

MacLeod

R. B.

(1932). An experimental investigation of brightness constancy. Archives of Psychology, 135, 5–102.

51.

Madsen

Donn

(2006). Experiments with a digital “light flow” meter in daylight art museum buildings. Paper presented at the 5th Radiance Scientific Workshop, Leicester UK, 13–14 September 2006.

52.

Maloney

L. T.

(2002). Illuminant estimation as cue combination. Journal of Vision, 2, 493–504.

53.

Maloney

L. T.

Gerhard

H. E.

Boyaci

Doerschner

(2010). Surface light perception and light field estimation in 3D scenes. In Harris

L. R.

Jenkin

(Eds.), Vision in 3D environments (pp. 65–88). Cambridge, England: Cambridge University Press.

54.

Mausfeld

(2013). The attribute of realness and the internal organization of perceptual reality. In Albertazzi

(Ed.), Handbook of experimental phenomenology: Visual perception of shape, space and appearance (pp. 91–118). Chichester, England: John Wiley & Sons, Ltd. doi:10.1002/9781118329016

55.

McColl

S. L.

Veitch

J. A.

(2001). Full-spectrum fluorescent lighting: A review on its effect on physiology and health. Psychological Medicine, 31, 949–964.

56.

Michel

(1996). Light: The shape of space. New York, NY: John Wiley & Sons.

57.

Morgenstern

Geisler

W. S.

Murray

R. F.

(2014). Human vision is attuned to the diffuseness of natural light. Journal of Vision, 14, 1–18. doi:10.1167/14.9.15

58.

Morgenstern

Murray

R. F.

Geisler

W. S.

(2010). Real world illumination measurements with a multidirectional photometer. Journal of Vision, 10, 444. doi:10.1167/10.7.444

59.

Morgenstern

Murray

R. F.

Geisler

W. S.

(2011). A low-dimensional statistical model of natural lighting. Journal of Vision, 11, 377. doi:10.1167/11.11.377

60.

Motoyoshi

Nishida

Sharan

Adelson

E. H.

(2007). Image statistics and the perception of surface qualities. Nature, 447, 206–209. doi:10.1038/nature05724

61.

Murari, M., Rodà, A., Canazza, S., De Poli, G. & Da Pos, O. (2015). Is Vivaldi smooth and takete? Non-verbal sensory scales for describing music qualities. Journal of New Music Research, 44, 359–372. Retrieved from https://doi.org/10.1080/09298215.2015.1101475

62.

Mury

A. A.

Pont

S. C.

Koenderink

J. J.

(2007). Spatial properties of light fields in natural scenes. In Y. De Kort (Ed.), Proceedings APGV 2007 (p. 140). New York, NY: ACM SIGGRAPH.

63.

Mury

A. A.

Pont

S. C.

Koenderink

J. J.

(2009). Structure of light fields in natural scenes. Applied Optics, 48, 5386–5395.

64.

Olkkonen

Brainard

D. H.

(2010). Perceived glossiness and lightness under real-world illumination. Journal of Vision, 10, 5. doi:10.1167/10.9.5

65.

Osgood

C. E.

(1956). Method and theory in experimental psychology. Oxford, England: Oxford University Press.

66.

O’Shea

J. P.

Agrawala

Banks

M. S.

(2010). The influence of shape cues on the perception of lighting direction. Journal of Vision, 10, 21. doi:10.1167/10.12.21

67.

Pentland

A. P.

(1982). Finding the illuminant direction. Journal of the Optical Society of America, 72, 448–455.

68.

Pont

S. C.

(2013). Spatial and form-giving qualities of light. In Albertazzi

(Ed.), Handbook of experimental phenomenology: Visual perception of shape, space and appearance (pp. 205–222). Chichester, England: John Wiley & Sons, Ltd. doi:10.1002/9781118329016

69.

Pont

S. C.

Koenderink

J. J.

(2007). Matching illumination of solid objects. Perception & Psychophysics, 69, 459–468. doi:10.3758/BF0319376

70.

Pont

S. C.

Mury

de Ridder

Koenderink

J. J.

(2009). Descriptions, measurements and visualization of light distributions in 3D spaces. In Y. De Kort (Ed.), Proceedings of Experiencing Light 2009 (pp. 74–78). Eindhoven, the Netherlands: Eindhoven University of Technology.

71.

R Core Team. (2016). R: A language and environment for statistical computing. Vienna, Austria: R Foundation for Statistical Computing. Retrieved from https://www.R-project.org/

72.

Schirillo

J. A.

(2013). We infer light in space. Psychonomic Bulletin Review, 20, 905–915. doi:10.3758/s13423-013-0408-1

73.

Scholl

B. J.

Tremoulet

P. D.

(2000). Perceptual causality and animacy. Trends in Cognitive Sciences, 4, 299–309. doi:10.1016/S1364-6613(00)01506-0

74.

Schöne

(1979). Über das Licht in der Malerei [About light in painting]. Berlin, Germany: Gebr.Mann Verlag.

75.

Schumann

(1920). Die Repräsentation des Leeren Raumes im Bewußtsein. Eine neue Empfindung [The representation of empty space in the consciousness. A new sensation]. Zeitschrift für Psychologie, 85, 224–244.

76.

Seuntiëns

P. J. H.

Vogels

(2008, October). Atmosphere creation: The relation between atmosphere and light characteristics. In Proceedings of the 6th International Conference on Design and Emotion (pp. 6–9). Hung Hom, Hong Kong: School of Design, The Hong Kong Polytechnic University.

77.

Stokkermans

Yuexu

Murdoch

M. J.

Heynderinckx

(2015, February). Effect of daylight on atmosphere perception: Comparison of a real space and visualizations. Proceedings of SPIE - The International Society for Optical Engineering, 9394, 1–15. doi:10.1117/12.2077078

78.

Stokkermans

M. G. M.

Vogels

I. M. L. C.

de Kort

Y. A. W.

Heynderickx

I. E. J.

(2017). Relation between the perceived atmosphere of a lit environment and perceptual attributes of light. Lighting Research and Technology. doi:10.1177/1477153517722384

79.

Toscani

Gegenfurtner

K. R.

Doerschner

(2017). Differences in illumination estimation in #thedress. Journal of Vision, 17, 22. doi:10.1167/17.1.22

80.

Vogels

(2008). Atmosphere metrics: Development of a tool to quantify experienced atmosphere. In Westerink

J. M. D. M.

Ouwerkerk

Overbeek

T. J. M.

Pasveer

W. F.

de Ruyter

(Eds.), Probing experience from assessment of user emotions and behaviour to development of products (pp. 25–41). New York, NY: Springer. doi:10.1007/978-1-4020-6593-4_3

81.

Vogels

de Vries

van Erp

(2008, June). Effect of coloured light on atmosphere perception. In I. Kortbawy, B. Bergström, & K. Fridell Anter (Eds.), Proceedings of the AIC Interim Meeting, Swedish Colour Centre Foundation (pp. 15–18). Stockholm, Sweden: AIC.

82.

Vos

J. J.

(2008). Depth in colour, a history of a chapter in physiologie optique amusante. Clinical and Experimental Optometry, 91, 139–147. doi:10.1111/j.1444-0938.2007.00212.x

83.

Wallach

(1976). On perception. New York, NY: Quadrangle/The New York Times Books Co.

84.

Wang

H. H.

Luo

M. R.

Liu

Yang

Zheng

Liu

(2014). A study of atmosphere perception of dynamic coloured light. Lighting Research and Technology, 46, 661–675. doi:10.1177/1477153513506591

85.

Xia

Pont

S. C.

Heynderinckx

(2013). Probing light in real scenes using optical mixtures. In L. Hoyet, B. Williams Sanders, J. Geigel, & J. Stefanucci (Eds.), Proceedings of the ACM Symposium on Applied Perception, Dublin (pp. 1–137).

86.

Xia

Pont

S. C.

Heynderinckx

(2014a). The influence of scene layout and content on the perception of light direction in real scenes. Journal of Vision, 14, 71. doi:10.1167/14.10.71

87.

Xia

Pont

S. C.

Heynderinckx

(2014b). The visual light field in real scenes. i-Perception, 5, 613–629. doi:10.1068/i0654

88.

Xia

Pont

S. C.

Heynderinckx

(2016). Effects of scene content and layout on the perceived light direction in 3D spaces. Journal of Vision, 16, 1–13. doi:10.1167/16.10

89.

Xia

Pont

S. C.

Heynderinckx

(2017). Separate and simultaneous adjustment of light qualities in a real scene. i-Perception, 8, 1–24. doi:10.1177/2041669516686089

90.

Zavagno

(2007). La percezione pittorica dello spazio [The pictorial perception of space]. Teorie & Modelli, 12, 111–138.

91.

Zavagno

Daneyko

(2008). When figure-ground segmentation modulates brightness: The case of phantom illumination. Acta Psychologica, 129, 166–174. doi:10.1016/j.actpsy.2008.05.011

92.

Zavagno

Daneyko

Sakurai

(2011). What can pictorial artifacts teach us about light and lightness? Japanese Psychological Research, 53, 448–462. doi:10.1111/j.1468-5884.2011.00488.x

93.

Zavagno

Massironi

(1997). La rappresentazione della luce nelle opere d'arte grafica [The representation of light in engravings]. Giornale Italiano di Psicologia, 24, 135–187. doi:10.1421/42

94.

Zavagno

Massironi

(2006). Colors in black and white: The depiction of brightness and lightness in achromatic engravings before the invention of photography. Perception, 35, 91–100. doi:10.1068/p5346

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