Hooijman, Maud (2024) The Relationship between Cognitively Driven Pupil Size Changes and Visual Processing. Bachelor thesis, Psychology.
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Abstract
Pupil size is not only influenced by environmental stimuli like brightness and distance, but also by cognitive processes. Pupil responses support the optimization of visual processing. They are initially driven by rods and cones. The different properties of these photoreceptors enable humans to have a rich visual experience. Pupil dilation and photoreceptor activity are closely related. Recent research has shown that pupil dilation led to a shift from rod- to cone-dominated vision in mice. We set up a visual detection task to test whether the same shift happens in humans. Participants fixated their eyes on a computer screen while red and blue targets appeared at different eccentricities. We found a detection advantage for both large pupils and peripheral targets. We also found an interaction effect between target color and eccentricity. We proposed that if the detection of blue and peripheral targets was less impaired by small pupils than by big pupils, that would point to a shift from rod- to cone-dominance. The detection of blue targets seemed to be less impaired by small pupils than the detection of red targets. The detection of peripheral targets was not less impaired by small pupils than the detection of parafoveal targets. Taken together, we have provided no hard evidence for a shift from rod- to cone-dominated vision in humans due to pupil dilation. However, there were indications that this shift could be existent. Additionally, limitations to our study could have significantly impacted our results. Future research should use refined experiments and more direct measures in order to provide more insight in the mechanisms underlying visual processing in humans.
| Item Type: | Thesis (Bachelor) |
|---|---|
| Supervisor name: | Ruuskanen, V.H.S. |
| Degree programme: | Psychology |
| Differentiation route: | None [Bachelor Psychology] |
| Date Deposited: | 07 Aug 2024 08:02 |
| Last Modified: | 07 Aug 2024 08:02 |
| URI: | http://gmwpublic.studenttheses.ub.rug.nl/id/eprint/4239 |
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