Eye-tracking data quality as affected by ethnicity and experimental design.

Lack of accuracy in eye-tracking data can be critical. If the point of gaze is not recorded accurately and reliably, the information obtained or action executed might be different from what the user intended. This study reports trackability, accuracy, and precision as indicators of eye-tracking data quality as measured at various head positions and light conditions for a sample of participants from three different ethnic groups. It was found that accuracy and precision for Asian participants was worse than that for African and Caucasian participants. No significant differences were found between the latter two ethnic groups. Operating distance had the largest effect on data quality, since it affected all indicators for all ethnic groups. Illumination had no significant effect on accuracy or precision, but the accuracy achieved by African and Caucasian participants was better when the stimulus was presented on a dark background. Large gaze angles proved to be detrimental for trackability for African participants, while accuracy and precision were also affected adversely by larger gaze angles for two of the ethnicities.