Investigation of the potential use of human eye pupil sizes to estimate visual sensations in the workplace environment

• This study showed the possible use of human eye's pupil size as a visual sensation index.
• Pupil sizes vary depending on subjects even in a same visual (lighting) condition.
• Individually normalized pupil size data reduce the undulation of the raw data.
• The change rates of pupil sizes seem consistent for all subjects.
• The change rates of pupil sizes per visual sensation are statistically significant.

Building occupants' environmental comfort and physiological health conditions are significantly affected by workplace environmental quality, such as lighting, thermal, air, and acoustic conditions. Of all of these factors, lighting quality is the most significant in relation to the occupants' visual comfort and health, since its effect is almost instantaneous, and it is vulnerable due to its immediate sensitivity. This research investigated the possibility of using human eye pupil sizes to estimate visual sensations in office workplace environments. The human body, as a biological mechanism, naturally makes unconditioned responses using the parasympathetic nervous system in multiple physical organs, including pupils in human eyes. Based on this physiological principle, a human body automatically reacts to ambient conditions to minimize any environmental stressful condition. This study adopted this principle as a key factor for analyzing pupil sizes and their change patterns to assess each individual subject's visual sensations while generating various ranges of ambient lighting conditions in an environmental chamber. The chamber is located at the University of Southern California where researchers conducted a series of human subject experiments. The collected data were analyzed using statistical tools for interpreting research findings. The data were grouped by the subjects' gender, age, glasses-worn, eye color, in order to identify any differences in pupil sizes and change rates, depending on the physical characteristics of each individual. These research findings indicated that the use of pupil sizes to assess a subject's visual sensations has potential and would be applicable to individuals, regardless of their physical characteristics.