Gaze Direction and Request Gesture in Social Interactions

Abstract

One of the most important faculties of humans is to understand the behaviour of other conspecifics. The present study aimed at determining whether, in a social context, request gesture and gaze direction of an individual are enough to infer his/her intention to communicate, by searching for their effects on the kinematics of another individual's arm action. In four experiments participants reached, grasped and lifted a bottle filled of orange juice in presence of an empty glass. In experiment 1, the further presence of a conspecific not producing any request with a hand and gaze did not modify the kinematics of the sequence. Conversely, experiments 2 and 3 showed that the presence of a conspecific producing only a request of pouring by holding the glass with his/her right hand, or only a request of comunicating with the conspecific, by using his/her gaze, affected lifting and grasping of the sequence, respectively. Experiment 4 showed that hand gesture and eye contact simultaneously produced affected the entire sequence. The results suggest that the presence of both request gesture and direct gaze produced by an individual changes the control of a motor sequence executed by another individual. We propose that a social request activates a social affordance that interferes with the control of whatever sequence and that the gaze of the potential receiver who held the glass with her hand modulates the effectiveness of the manual gesture. This paradigm if applied to individuals affected by autism disorder can give new insight on the nature of their impairment in social interaction and communication.

Type of gesture, valence, and gaze modulate the influence of gestures on observer's behaviors

“…Concerning request gestures, this was observed in previous studies where the authors found that the kinematics of reaching-grasping and placing and those of reaching-grasping and lifting were altered by the request gestures “give-me-in-the-hand” (Sartori et al, 2009), “feed-me” (Ferri et al, 2011) and “pour” (Innocenti et al, 2012). The fact that gestures understanding and responses preparing are interlaced processes also comes from a fMRI study (Newman-Norlund et al, 2007).…”

“…Thus, we expected interference of the type of gesture with the actual action, which, however, could be stronger for request than symbolic gestures. The interference could induce movement slowing down or veering away from the gesturing conspecific (Tipper et al, 1991, 1997; De Stefani et al, 2012; Innocenti et al, 2012). …”

Joint Action: Mental Representations, Shared Information and General Mechanisms for Coordinating with Others

“…Joint attention relies on co-actors’ ability to monitor each other’s gaze and attentional states (Emery, 2000). For instance, when synchronizing actions, co-actors divide attention between locations relevant for their own and for their co-actor’s goal (Kourtis et al, 2014; see Böckler et al, 2012; Ciardo et al, 2016 for similar results using different tasks), and sharing gaze affects object processing by making attended objects motorically and emotionally more relevant (Becchio et al, 2008; Innocenti et al, 2012; Scorolli et al, 2014). Moreover, in a joint search task, co-actors who mutually received information about each other’s gaze location via different sensory modalities (i.e., vision, audition, and touch) searched faster than without such information (Brennan et al, 2008; Wahn et al, 2015).…”

Through your eyes: incongruence of gaze and action increases spontaneous perspective taking

“…Gaze is an important source of information about others' intentions and actions (Allison et al, 2000; Mennie et al, 2007; Becchio et al, 2008; Pierno et al, 2008; Sartori et al, 2009; Innocenti et al, 2012). From the gaze of another person, we can infer what the person is interested in, what she might desire, and, consequently, what she will do next (Pierno et al, 2006).…”

“…Participants were presented with brief videos (rather than still photographs) depicting two objects, a milk cartoon and a glass full of milk, on a table, with or without a person behind (see Figure 1). Because looking at an object often signals intention to act on the object (Allison et al, 2000; Mennie et al, 2007; Becchio et al, 2008; Pierno et al, 2008; Sartori et al, 2009; Innocenti et al, 2012), the tendency to take the actor's perspective should be stronger when the actor looks at one of the objects and even stronger when the actor reaches toward the object.…”