Like Robots, Like Humans: Pupil Dilation during Collaborative Object Manipulation

It is well known that pupil dilation reflects an increase in cognitive load during tasks that demand mental effort. Inspired by this, we questioned whether the same effect occurs during social interactions, particularly in joint object manipulation tasks that require attention and coordination for successful completion. In the first scenario, we measure pupil dilation during human-human interactive actions (handover), either as the object giver or receiver, against an individual action (pick-and-place). In the second scenario, pupillometry is associated with human-to-robot handovers. We present the two publicly available datasets collected in these contexts. Our results show a strong link between pupil dilation and collaborative actions, with both humans and robots. Indeed, an increment in pupil size corresponds to the object handover, which presents the added complexity of mutual coordination. Conversely, individual actions do not elicit the same physiological response at the level of the pupil. In both scenarios, we used objects with different physical properties, cups with varying water levels, but this factor influenced pupil dilation (and presumably, the mental workload) only during the interaction with the robot. With this study, we explore pupillometry as a physiological metric to evaluate cognitive load for collaborative object manipulation during human-human or human-robot collaborations.