Pupil-assisted target selection (PATS): State of the art and future prospects

Affective interaction is assumed to advance interacting among humans and technical systems. Using pupil size as affective information, we review hitherto presented approaches for pupil-based interaction. Three approaches base on different mechanisms; pupil size changes produced by covertly attending towards a set of stimuli changing in brightness, changes in pupil diameter actively produced by the user, and those occurring automatically as a by-product of cognitive processes. While the first two approaches can produce effective but relatively slow target selections, the latter might allow faster selections, but has to be combined with other selection mechanisms. Reanalyzing two data sets obtained with this most promising approach of using cognitive processes as basis for pupil-based target selection, it turns out that despite of differences in task and brightness, signal dynamics are characterized by comparable latencies and effect sizes. These may lay the foundation for future investigations into pupil diameter changes accompanying object selection in human-robot interaction. Finally, we suggest further investigations into the subject, determining when and why pupil diameter changes accompany object selections.