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.

Evaluation of Daylight Perception Assessment Methods

“…However, some studies ( Galasiu and Veitch, 2006 ; Bellia et al, 2017 ; Lo Verso et al, 2021 ) have shown that correspondence between exposed daylight conditions and subjective assessment of the occupants is not always observed because of individual differences. Subjective assessment methods mainly use questionnaires to obtain information through semantic differential techniques, measuring the participant’s overall reaction to specific factors such as ambient illumination of different light sources or horizontal illuminance and brightness of a space ( Jin et al, 2017 ; Albertazzi et al, 2018 ). Similarly, open-ended questions are used to gain deeper and new insights into the feelings towards daylight conditions, for instance, asking how participants describe the lighting conditions and how they feel under those conditions.…”

Experimental phenomenology for consciousness.

“…Each component of the perceived scene, after a careful observation and description of its behavior, can be experimentally verified, measured and modeled in controlled conditions. Consider explaining the experience of the sensual light of the sunset (Albertazzi, Canal, Chisté, Micciolo, & Zavagno, 2018) or how the morphology of shapes naturally conveys sound, color, touch, and taste (Albertazzi, Canal, da Pos, et al, 2013; Albertazzi, Bacci, Canal, & Micciolo, 2016; Dadam, Albertazzi, da Pos, Canal, & Micciolo, 2012). Methods, models, measurement tools, and statistical analyses, however, must be properly chosen because the observables of the scenes are not physical cues (see below).…”

The perception of light from a phenomenological perspective.

“…As such, they are manifestations of light. Environmental illumination concerns the brightness of spaces and the quality of the light filling, so to speak, the air (Albertazzi et al, 2018). To better understand the experience related to environmental illumination, consider a room illuminated by 20 candles placed on a table in the center of the room.…”

“…Brightness aside, environmental illumination appears to possess also many other perceptual qualities in relation to different types of illuminants. In this respect, the research conducted by Albertazzi et al (2018) on the phenomenological appearance of environmental illumination shows not only that environmental illumination is a perceptual presence, but also the light that constitutes it is seen to possess peculiar visible features that allows for specific categorizations of the type of visual experiences and probably also affective experiences associated with environmental illumination. I hold that a better understanding of these qualitative aspects may help identify underlying factors that may be of interest also for other research fields, such as architecture and lighting design.…”