09-07-2020, 08:59 AM
To ensure the highest data quality, the background color of your calibration, validation, and drift-check screens should match the average brightness (luminance) of the screens displaying your experimental stimuli.
Follow this simple guide:
Why This Matters
Drastic changes in screen brightness between calibration and the actual trial will cause the participant's pupils to dilate or constrict. Because this change is not perfectly symmetrical, it can introduce a small but significant error, or "drift," into the recorded gaze data. Maintaining a consistent luminance minimizes these pupil size changes and leads to more accurate data.
Follow this simple guide:
- For experiments with a uniform background: If your stimuli are presented on a consistent background (e.g., white or black), use that same color for all calibration screens.
- For experiments with a variable background: If your stimuli vary in brightness (e.g., a mix of full-screen natural images), use a neutral, mid-gray background for all calibration screens.
Why This Matters
Drastic changes in screen brightness between calibration and the actual trial will cause the participant's pupils to dilate or constrict. Because this change is not perfectly symmetrical, it can introduce a small but significant error, or "drift," into the recorded gaze data. Maintaining a consistent luminance minimizes these pupil size changes and leads to more accurate data.