The art of pervasive eye tracking

Pervasive mobile eye tracking provides a rich data source to investigate human natural behavior, providing a high degree of ecological validity in natural environments. However, challenges and limitations intrinsic to unconstrained mobile eye tracking makes its development and usage to some extent an art. Nonetheless, researchers are pushing the boundaries of this technology to help assess museum visitors' attention not only between the exhibited works, but also within particular pieces, providing significantly more detailed insights than traditional timing-and-tracking or external observer approaches. In this paper, we present in detail the eye tracking system developed for a large scale fully-unconstrained study in the Austrian Gallery Belvedere, providing useful information for eye-tracking system designers. Furthermore, the study is described, and we report on usability and real-time performance metrics. Our results suggest that, although the system is comfortable enough, further eye tracker improvements are necessary to make it less conspicuous. Additionally, real-time accuracy already suffices for simple applications such as audio guides for the majority of users even in the absence of eye-tracker slippage compensation.