Ramuel Segal
Ph.D.Thesis, 2023 (direct track)
(together with Efrat Eizenberg)
ABSTRACT:
Light influences almost every experience in our lives. It enables life on earth and is responsible for growth, health, the functioning of the biological clock and the circadian rhythm. In the past, daylight was the main source of light in buildings. However, since electric lighting has become accessible and reliable, a significant part of the population spends most of its daytime in manmade buildings. Thus, people are exposed to various physical elements, such as electric lighting, to which they react physiologically, mentally and emotionally, just like they react to natural sources of light.
Until today many studies have focused on the subjective assessment of light. Most of these studies rely solely on quantitative methodology based on an analysis of the ranking of adjectives or statements. A review of the scales that were used in these studies, demonstrates significant versatility in the characteristics and scope of questionnaires. In addition, many studies seek to evaluate the effect of light and lighting on mood or on wellbeing. Those, naturally, have to do with all fields of life, and call for a broad, prolonged examination, well beyond the more basic levels of experience. Thus, despite the consensus around and increased engagement with the study of the subjective assessment of light in the past five decades, the research field has struggled to formulate consistent conclusions, insights or recommendations for design of any kind.
Today it is clear that perception is not a passive process but a cognitive process of generating meaningful patterns from raw sensory information, based on prior knowledge and experiences. Vision too is an active process of internal groping and discourse in which the environment, light, sensation, perception and cognition are engaged until the emergence of meaning. Recognizing the subjective dimension of researched reality calls for a study of the world around us from within our experience as well. Drawing on these insights and distinctions, this research was conducted through a phenomenological approach which deals with a study of phenomena as they are experienced.
This research constitutes a broad and profound study of light experience that applies a phenomenological approach and a mixed, qualitative and quantitative, research methodology. It aims to serve as an inquiry regarding the relationship between different artificial lighting environments and light experience. The research includes a characterization of light experience through seven semi-structured in-depth interviews of experts and an experiment which examined the relationship between various artificial lighting environments and light experience. In the framework of the experiment, participants [N=116] evaluated their experience in a structured questionnaire, and the ranking of adjectives. This research design allows a proposal of explanations for the quantitative results of the ranking.
The analysis in this study offers a broad perspective and an in-depth observation of the experience of light and of phenomena pertaining to the properties of light, of its relationship with the environment, of the meaning attributed to light, of prior knowledge, place and time, of activity and the representation of experience by adjectives. The analysis of light properties in itself attests to the impact of emotions, thoughts, images and past experiences on even basic sensation. In this framework, subjectivity, variation, ambivalence and at times even preference, are all evident to a significant extent in anything related to the perception of these physical and ostensibly ‘objective’ properties. A narrowed gaze and averted head, to the extent of actual physical tension, are added to the effects of discomfort glare known in the professional literature. The analysis also presents a new conception regarding visual clarity, represented by lucid versus clear vision or environment. In a lucid environment it is easier and more convenient to observe hues and details, to discern between them without glare. In a clear environment, on the other hand, space, shapes, colors, shadow and texture are experienced in an acute, clear and realistic manner. The experience pertaining to visual task performance includes reference to three main activity typologies: low, medium and high visual effort, and it too, is characterized by significant variance.
Manifestations of meaning attributed to light and darkness bestow new dimensions upon the understanding of light experience and are linked to atmosphere, to an experience of being in light, and to activity. On the path to convergence and naming the experience awaits a long list of preconceptions, mainly regarding CCT and intensity. A very dominant preconception refers to florescent and luminous efficacy, mainly in direct white lighting. Alongside its appreciation as economical, it is very negatively tied to institutional lighting due to its tone and glare, as well as the visual presence of the lighting fixtures, their linear or uniform layout. Another significant complex of preconceptions pertains to the connection that may be established between experiences linked to electric lighting and those linked to natural lighting in terms of aspects of CCT, intensity, layout, discerning details, shadow, time, season and place. The last layer of preconceptions offers a profound understanding of the cognitive and emotional implications inherent to the relationship between lighting conditions and familiar place, time or activity. An analysis of the emotions named in routine language points to a common use of negative expressions, such as ‘no’, or ‘less’, of place-affiliated expressions as direct sensory adjectives, and to the convergence of emotions to one of two categories of either pleasant or unpleasant.
Based on the results, two mechanisms for weighing the experience are also proposed One has to do with the preference that embodies the weighing of one experience against another. The most prominent preference is linked to warm white lighting over cool white lighting, after which ranks the preference for indirect light over direct light. The balanced preference between high and low intensity at the end of the process reflects the participants’ ‘discovery’ of sorts, shifting between the basic attraction of high illuminance level and ambience and the possibilities affiliated with a low illuminance level. The preferred uses analysis points to a longing for ambience lighting at a much broader range of places or activities than those acknowledged today, while the preference for strong, direct lighting is reserved mainly to considerations pertaining to a sense of security in the public spaces, activities requiring precision, or as external motivators. The second weighing mechanism is presented through characterizing ‘experience profile’ of a lighting condition, and an extended mapping of the light experience, offering yet another contribution to the body of knowledge. The light profiles allow the laying out of a multitude of facets of light experience regarding each of the lighting conditions. The extended mapping enables a broader, more mature and responsible comprehension of light experience, with or without regard to the ranking’s significant results.