Temporal Order Judgements of Dynamic Gaze Stimuli Reveal a Postdictive Prioritisation of Averted Over Direct Shifts

The impact of facial expression and communicative gaze of a humanoid robot on individual Sense of Agency

Sense of Agency (SoA) is the feeling of control over one's actions and their outcomes. A well-established implicit measure of SoA is the temporal interval estimation paradigm, in which participants estimate the time interval between a voluntary action and its sensory consequence. In the present study, we aimed to investigate whether the valence of action outcome modulated implicit SoA. The valence was manipulated through interaction partner's (i) positive/negative facial expression, or (ii) type of gaze (gaze contact or averted gaze). The interaction partner was the humanoid robot iCub. In Experiment 1, participants estimated the time interval between the onset of their action (head movement towards the robot), and the robot's facial expression (happy vs. sad face). Experiment 2 was identical, but the outcome of participants' action was the type of robot's gaze (gaze contact vs. averted). In Experiment 3, we assessed-in a within-subject design-the combined effect of robot's type of facial expression and type of gaze. Results showed that, while the robot's facial expression did not affect participants' SoA (Experiment 1), the type of gaze affected SoA in both Experiment 2 and Experiment 3. Overall, our findings showed that the robot's gaze is a more potent factor than facial expression in modulating participants' implicit SoA.

Assumptions about the positioning of virtual stimuli affect gaze direction estimates during Augmented Reality based interactions

We investigated gaze direction determination in dyadic interactions mediated by an Augmented Reality (AR) head-mounted-display. With AR, virtual content is overlaid on top of the real-world scene, offering unique data visualization and interaction opportunities. A drawback of AR however is related to uncertainty regarding the AR user’s focus of attention in social-collaborative settings: an AR user looking in our direction might either be paying attention to us or to augmentations positioned somewhere in between. In two psychophysical experiments, we assessed what impact assumptions concerning the positioning of virtual content attended by an AR user have on other people’s sensitivity to their gaze direction. In the first experiment we found that gaze discrimination was better when the participant was aware that the AR user was focusing on stimuli positioned on their depth plane as opposed to being positioned halfway between the AR user and the participant. In the second experiment, we found that this modulatory effect was explained by participants’ assumptions concerning which plane the AR user was focusing on, irrespective of these being correct. We discuss the significance of AR reduced gaze determination in social-collaborative settings as well as theoretical implications regarding the impact of this technology on social behaviour.