Most experimental protocols examining joint attention with the gaze cueing paradigm are “observational” and “offline”, thereby not involving social interaction. We examined whether within a naturalistic online interaction, real-time eye contact influences the gaze cueing effect (GCE). We embedded gaze cueing in an interactive protocol with the iCub humanoid robot. This has the advantage of ecological validity combined with excellent experimental control. Critically, before averting the gaze, iCub either established eye contact or not, a manipulation enabled by an algorithm detecting position of the human eyes. For non-predictive gaze cueing procedure (Experiment 1), only the eye contact condition elicited GCE, while for counter-predictive procedure (Experiment 2), only the condition with no eye contact induced GCE. These results reveal an interactive effect of strategic (gaze validity) and social (eye contact) top-down components on the reflexive orienting of attention induced by gaze cues. More generally, we propose that naturalistic protocols with an embodied presence of an agent can cast a new light on mechanisms of social cognition.

Eye contact constitutes a strong communicative signal in human interactions and has been shown to modulate various cognitive processes and states. However, little is known about its impact on gazemediated attentional orienting in the context of its interplay with strategic top-down control. Here, we aimed at investigating how the social component of eye contact interacts with the top-down strategic control. To this end, we designed a gaze cuing paradigm with the iCub humanoid robot, in which iCub either established eye contact with the participants before averting its gaze or avoided their eyes. Across four experiments, we manipulated gaze cue validity to either elicit strategic top-down inhibitory activity (25% validity) or to allow for relaxing the control mechanisms (50% validity). Also, we manipulated the stimulus-onset-asynchrony (SOA) to examine the dynamics of the top-down modulatory effects. Our results showed that eye contact influenced the gaze cuing effect when the strategic control was not required, by prolonging the prioritized processing of the gazed-at locations. Thus, the effect was observed only when the measurement was taken after a sufficient amount of time (1,000 ms SOA). However, when inhibitory control was necessary (25% validity), the social component was not potent enough to exert influence over the gaze cuing effect independently. Overall, we propose that strategic top-down control is the primary driving force over the gaze cuing effect and that the social aspect plays a modulatory effect by prolonging prioritized processing of gazed-at locations.

This paper reports a study where we examined how a humanoid robot was evaluated by users, dependent on established eye contact. In two experiments, we manipulated how the robot gazes, namely either by looking at the subjects' eyes (mutual gaze) or to a socially neutral position (neutral). Across the two experiments, we altered the level of predictiveness of the robot's gaze direction with respect to a subsequent target stimulus (in Exp.1 the direction was non-predictive, in Exp. 2 the gaze direction was counter-predictive). Results of subjective reports showed that participants were sensitive to eye contact. Moreover, participants were more engaged and ascribed higher intentionality to the robot in the mutual gaze condition relative to the neutral condition. This was independent of predictiveness of the gaze cue. Our results suggest that embodied humanoid robots can establish eye contact, which in turn has a positive impact on perceived socialness of the robot, and on the quality of human-robot interaction (HRI). Therefore, establishing mutual gaze should be considered in design of robot behaviors for social HRI.

Most experimental protocols examining joint attention with the gaze cueing paradigm are “observational” and “offline”, thereby not involving social interaction. We examined whether within a naturalistic online interaction, real-time eye contact influences the gaze cueing effect (GCE). We embedded gaze cueing in an interactive protocol with the iCub humanoid robot. This has the advantage of ecological validity combined with excellent experimental control. Critically, before averting the gaze, iCub either established eye contact or not, a manipulation enabled by an algorithm detecting position of the human eyes. For non-predictive gaze cueing procedure (Experiment 1), only the eye contact condition elicited GCE, while for counter-predictive procedure (Experiment 2), only the condition with no eye contact induced GCE. These results reveal an interactive effect of strategic (gaze validity) and social (eye contact) top-down components on the reflexive orienting of attention induced by gaze cues. More generally, we propose that naturalistic protocols with an embodied presence of an agent can cast a new light on mechanisms of social cognition.

This article reviews methods to investigate joint attention and highlights the benefits of new methodological approaches that make use of the most recent technological developments, such as humanoid robots for studying social cognition. After reviewing classical approaches that address joint attention mechanisms with the use of controlled screen-based stimuli, we describe recent accounts that have proposed the need for more natural and interactive experimental protocols. Although the recent approaches allow for more ecological validity, they often face the challenges of experimental control in more natural social interaction protocols. In this context, we propose that the use of humanoid robots in interactive protocols is a particularly promising avenue for targeting the mechanisms of joint attention. Using humanoid robots to interact with humans in naturalistic experimental setups has the advantage of both excellent experimental control and ecological validity. In clinical applications, it offers new techniques for both diagnosis and therapy, especially for children with autism spectrum disorder. The review concludes with indications for future research, in the domains of healthcare applications and human-robot interaction in general.