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

The Hong Kong Polytechnic University128 enrolled

Overview

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.

Colour perception and binocular rivalry both show variability across individuals. However, the extent to which these individual differences are stable and whether they are associated with personal or physiological factors remains unclear. This study will use behavioural visual perception tasks to measure individual differences in colour perception and binocular rivalry. Participants will complete a colour perception task and a binocular rivalry task, along with questionnaire measures related to chronotype, sleep, fatigue, and demographic characteristics including sex. The primary aim is to determine whether measurable individual differences are present in colour perception and binocular rivalry performance. The secondary aim is to examine whether these differences are associated with chronotype, sex, sleep-related variables, and subjective fatigue. The study is observational and does not involve a clinical intervention, drug, biologic product, or medical device.

Study Type

OBSERVATIONAL

Enrollment

128

Conditions

Colour Perception Color Perception Binocular Rivalry

Eligibility

Sex: ALLMin age: 18 YearsMax age: 25 YearsHealthy volunteers:

Medical Language ↔ Plain English

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.

Outcomes

Primary Outcomes

Mean colour-adjustment values on the colour perception task

Colour perception will be measured using a computer-based colour adjustment task. Participants will adjust the appearance of a target object or stimulus, and outcome variables will include adjustment values in colour space, such as chromaticity, hue, saturation, or luminance-related measures, depending on the final task implementation. These measures will be used to characterise individual differences in colour perception.

Time frame: Day 1 (single laboratory session)

Mean perceptual dominance duration during binocular rivalry

Binocular rivalry is measured with a computer-based dichoptic task in which a different image is presented to each eye. Perceptual dominance duration is the mean length of time, in seconds, that one stimulus remains exclusively visible before perception switches to the other. Longer mean durations indicate more stable, slower-switching rivalry.

Time frame: Day 1 (single laboratory session)

Mean alternation rate during binocular rivalry

Binocular rivalry is measured with the same computer-based dichoptic task. Alternation rate is the mean number of perceptual switches between the two stimuli per minute of viewing. Higher alternation rates indicate faster perceptual switching between the two eyes' images.

Time frame: Day 1 (single laboratory session)

Secondary Outcomes

Morningness-Eveningness Questionnaire (MEQ) score

Chronotype assessed using the Morningness-Eveningness Questionnaire (MEQ). Total scores range from 16 to 86; higher scores indicate greater morningness (a stronger morning-type preference) and lower scores indicate greater eveningness.

Time frame: Day 1 (single laboratory session)

Pittsburgh Sleep Quality Index (PSQI) global score

Sleep quality assessed using the Pittsburgh Sleep Quality Index (PSQI). The global score is the sum of seven component scores and ranges from 0 to 21; higher scores indicate worse sleep quality (a global score above 5 indicates poor sleep quality).

Time frame: Administered once, within 7 days before or at the single laboratory session (Day 1); the PSQI assesses sleep over the preceding 1 month.

Karolinska Sleepiness Scale (KSS) score

Subjective sleepiness/fatigue assessed using the Karolinska Sleepiness Scale (KSS), a single-item 9-point scale. Scores range from 1 to 9; higher scores indicate greater sleepiness. The pre-task to post-task change in KSS score may also be reported.

Time frame: Day 1: assessed immediately before and immediately after the visual perception tasks, which are completed within a single session lasting up to approximately 1 hour.

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

Overview

Conditions

Interventions

Eligibility

Locations (2)

Outcomes

Primary Outcomes

Secondary Outcomes

Central Contacts