THE OFFICIAL JOURNAL OF THE INTERNATIONAL CONGRESS OF INFANT STUDIES Infancy, 20(6), 601–633, 2015 Copyright © International Congress of Infant Studies (ICIS) ISSN: 1525-0008 print / 1532-7078 online DOI: 10.1111/infa.12093 Consequences of Eye Color, Positioning, and Head Movement for Eye-Tracking Data Quality in Infant Research Roy S. Hessels Department of Experimental Psychology, Helmholtz Institute, Utrecht University and Department of Developmental Psychology, Utrecht University Richard Andersson Eye Information Group, IT University of Copenhagen and Department of Philosophy & Cognitive Science Lund University Ignace T. C. Hooge Department of Experimental Psychology, Helmholtz Institute Utrecht University Marcus Nystrom€ Humanities Laboratory Lund University Chantal Kemner Department of Experimental Psychology, Helmholtz Institute, Utrecht University and Department of Developmental Psychology, Utrecht University and Brain Center Rudolf Magnus University Medical Centre Utrecht Correspondence should be sent to Roy S. Hessels, Heidelberglaan 1, 3584 CS Utrecht, The Netherlands. E-mail:
[email protected] 602 HESSELS ET AL. Eye tracking has become a valuable tool for investigating infant looking behavior over the last decades. However, where eye-tracking methodology and achieving high data quality have received a much attention for adult participants, it is unclear how these results generalize to infant research. This is particularly important as infants behave different from adults in front of the eye tracker. In this study, we investigated whether eye physiology, posi- tioning, and infant behavior affect measures of eye-tracking data quality: accuracy, precision, and data loss. We report that accuracy and precision are lower, and more data loss occurs for infants with bluish eye color com- pared to infants with brownish eye color.