Fraser, Paige A (2024) Shedding Light on Pupil Responses: Exploring the Association Between Light Exposure History and Pupil Biomarkers. Honours thesis, University of Southern Queensland. (Unpublished)
Abstract
The influence of environmental light exposure on visual and non-visual responses is well established, with recent research highlighting pupil biomarkers, such as the Post-Illumination Pupil Response (PIPR), a promising tool for assessing light-driven physiological changes. However, the sensitivity of the PIPR to individual light exposure histories remains poorly understood, particularly when comparing the contributions of non-image forming (M-EDI) and image-forming (photopic lux) light exposure. This study determines the influence of these two distinct light exposure measures on PIPR amplitude, over a two-week period. Nine participants, five males and four females with a mean age of 25.44 (SD = 7.02) wore actigraphs to measure their daily light exposure over two two-week periods with PIPR measurements taken at two time points. The results indicate a strong positive correlation between M-EDI and photopic lux, r(34) = .99, p <.001, and strong negative correlations between M-EDI and PIPR amplitude, r(34) = -.63, p = <.001, and photopic lux and PIPR amplitude, r(34) = -.61, p = <.001. This indicates shared explanatory power between both light measures however, partial correlations showed these results to be non-significant when controlling for one independent variable. Strong negative correlations were also found between PIPR amplitude and both M-EDI on day one, r(17) = -.60, p = .012, and M-EDI on day 13, r(16) = -.53, p = .038. Day one was slightly stronger, suggesting that distal light exposure may have a stronger effect than proximal light exposure on the PIPR. The findings suggest that increased light exposure can increase an individual’s sensitivity to light and indicates an adaptation process in the non-image forming vision system, similar to that of the image-forming vision system, which has been greatly investigated. Further research is required to understand the unique influence of each light exposure on pupil mechanisms and how they adapt to fluctuating light changes amongst different populations and in different environments such as, indoor versus outdoor exposure. This would help to better understand v the thresholds at which light exposure is optimal for healthy pupil functioning and thresholds that fail to alter an individual’s sensitivity to light.
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| Item Type: | Thesis (Non-Research) (Honours) |
|---|---|
| Item Status: | Live Archive |
| Additional Information: | Current UniSQ staff and students can request access to this thesis. Please email research.repository@unisq.edu.au with a subject line of SEAR thesis request and provide: Name of the thesis requested and Your name and UniSQ email address |
| Faculty/School / Institute/Centre: | Current – Faculty of Health, Engineering and Sciences - School of Psychology and Wellbeing (1 Jan 2022 -) |
| Supervisors: | Dr Joyce, Daniel |
| Qualification: | Bachelor of Psychology (Honours) |
| Date Deposited: | 21 Jan 2026 06:25 |
| Last Modified: | 21 Jan 2026 06:25 |
| Uncontrolled Keywords: | light exposure, melanopic, photopic, post-illumination pupil response (PIPR), pupil biomarker. |
| Fields of Research (2008): | 17 Psychology and Cognitive Sciences > 1701 Psychology > 170106 Health, Clinical and Counselling Psychology |
| Fields of Research (2020): | 52 PSYCHOLOGY > 5203 Clinical and health psychology > 520304 Health psychology |
| URI: | https://sear.unisq.edu.au/id/eprint/53088 |
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