The validation of online webcam-based eye-tracking: The replication of the cascade effect, the novelty preference, and the visual world paradigm

Abstract

The many benefits of online research and the recent emergence of open-source eyetracking libraries have sparked the interest in transferring time-consuming and expensive eyetracking studies from lab to web. In the current study, we validate online webcam-based eyetracking by replicating three robust eye-tracking studies (the cascade effect, the novelty preference, and the visual world paradigm) online using the participant's webcam as eye-tracker with the WebGazer.js library. We successfully replicated all three effects, although the effect sizes of all three studies shrank by 20 to 27%. The visual world paradigm was not only conducted online but also in the lab, using the same participants and a standard laboratory eye-tracker. This showed that replication per se could not fully account for the effect size shrinkage, but that the shrinkage is also due to the use of online webcam-based eyetracking, which is noisier. In conclusion, we argue that eye-tracking studies with relatively large effects that do not require extremely high precision can be done online using the participant’s webcam. We also make recommendations for how the quality of online webcam-based eye-tracking could be improved.