Visual Perception, Binocular Rivalry, and Fatigue-Related Individual Differences in Colour and Illumination Judgement

This observational study aims to characterise individual differences in colour perception and binocular rivalry. Participants will complete computer-based visual perception tasks, including a colour perception task and a binocular rivalry task. The study will first examine whether individuals show measurable differences in these perceptual responses. It will then explore whether these differences are associated with chronotype, sex, sleep-related measures, and subjective fatigue. The findings may help clarify how stable individual characteristics and daily physiological states relate to visual perception.

Inclusion Criteria: * Adults aged 18 years or older. * Normal or corrected-to-normal visual acuity. * Normal or corrected-to-normal binocular vision. * Normal colour vision, or no self-reported colour vision deficiency. * Able to understand the study instructions and provide informed consent. * Able to complete computer-based visual perception tasks and self-report questionnaires. Exclusion Criteria: * Self-reported colour vision deficiency. * Uncorrected visual impairment or eye conditions that may interfere with visual perception tasks. * Strabismus, amblyopia, or other binocular vision problems that may interfere with binocular rivalry testing. * History of neurological disorders, photosensitive epilepsy, or severe sensitivity to flickering visual stimuli. * Current condition or medication that, in the investigator's judgment, may substantially affect visual perception, attention, or task performance. * Inability to complete the task procedures or provide valid responses.