Looking Forward: Comment on Morgante, Zolfaghari, and Johnson.

Morgante et al. (in press) find inconsistencies in the time reporting of a Tobii T60XL eye tracker. Their study raises important questions about the use of the Tobii T-series in particular, and various software and hardware in general, in different infant eye tracking paradigms. It leaves open the question of the source of the inconsistencies. Here, observations from a Tobii eye tracker are presented to elucidate possible sources of timing inconsistencies, including those found by Morgante et al. The ramifications of the reported timing inconsistencies are related to various infant paradigms. The focus is on the level of concern a researcher should have if any eye tracker displays these timing characteristics, and what corrective measures may be taken. While posing no problems for some paradigms, timing inconsistencies are potentially problematic (but correctable) when assessing event-related looking behavior. Observed timing contraindicates use in fast gaze-contingent displays (<100 ms). General suggestions are made regarding timing in eye-tracked data collection.