09-04-2020, 03:06 PM
Ambient room lighting will not interfere with the operation of the EyeLink system, as the system works entirely in the infrared spectrum. However, harsh sources of infrared light (sunlight, other IR emitting devices etc.) can interfere with the system’s ability to accurately track the eye. You can minimize other sources of infrared light, by doing things such as disabling other infrared illumination sources and avoiding using the system under direct sunlight while tracking.
Ambient lighting levels can also affect the size of the participant's pupil. Typically, it is a good idea to make sure that the room lighting is as consistent as possible during a recording session, and across sessions, especially if measuring pupil size. Large changes in pupil size can have adverse effects on the accuracy of the gaze data. For instance, turning the light off in the middle of a recording session could result in a large increase in pupil size, and a consequent shift in the reported gaze location (pupils do not dilate / constrict symmetrically around their center). Similarly, be sure to keep the illumination of the experimental display screens are roughly the same (i.e. betweeen eye tracker calibration / validation to stimulus presentation).
Ambient lighting levels can also affect the size of the participant's pupil. Typically, it is a good idea to make sure that the room lighting is as consistent as possible during a recording session, and across sessions, especially if measuring pupil size. Large changes in pupil size can have adverse effects on the accuracy of the gaze data. For instance, turning the light off in the middle of a recording session could result in a large increase in pupil size, and a consequent shift in the reported gaze location (pupils do not dilate / constrict symmetrically around their center). Similarly, be sure to keep the illumination of the experimental display screens are roughly the same (i.e. betweeen eye tracker calibration / validation to stimulus presentation).