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

Abstract

The present kinematic study aimed at determining whether the observation of arm/hand gestures performed by conspecifics affected an action apparently unrelated to the gesture (i.e., reaching-grasping). In 3 experiments we examined the influence of different gestures on action kinematics. We also analyzed the effects of words corresponding in meaning to the gestures, on the same action. In Experiment 1, the type of gesture, valence and actor's gaze were the investigated variables Participants executed the action of reaching-grasping after discriminating whether the gestures produced by a conspecific were meaningful or not. The meaningful gestures were request or symbolic and their valence was positive or negative. They were presented by the conspecific either blindfolded or not. In control Experiment 2 we searched for effects of the sole gaze, and, in Experiment 3, the effects of the same characteristics of words corresponding in meaning to the gestures and visually presented by the conspecific. Type of gesture, valence, and gaze influenced the actual action kinematics; these effects were similar, but not the same as those induced by words. We proposed that the signal activated a response which made the actual action faster for negative valence of gesture, whereas for request signals and available gaze, the response interfered with the actual action more than symbolic signals and not available gaze. Finally, we proposed the existence of a common circuit involved in the comprehension of gestures and words and in the activation of consequent responses to them.

The Use of Hyperscanning to Investigate the Role of Social, Affective, and Informative Gestures in Non-Verbal Communication. Electrophysiological (EEG) and Inter-Brain Connectivity Evidence

“…This result appears in agreement with our initial hypothesis, confirming the theory of neural signatures of affective experience [20,21,70], which postulates an increase of left-brain responsiveness according to positive stimuli, inducing an "approaching behavior", compared to negative ones, which provides an increase of right-brain responsiveness inducing an "avoidance behavior" [71].…”

The combined effects of motor and social goals on the kinematics of object-directed motor action

“…For instance, exploring a cooperative motor task, Quesque and Coello 38 reported that the spatial amplification of a grasp-to-place motor action was broader, resulting in a higher arm trajectory, when the partner's eye-level was set at a higher position. This result is in line with the key role of the gaze in the process of action understanding in social contexts [39][40][41][42][43] . Because of their social value, the spatio-temporal variations of object-directed motor actions are also thought to serve as crucial cues for an observer to identify the agent's social goal [44][45][46] .…”

Pupils say more than a thousand words: Pupil size reflects how observed actions are interpreted

“…Even if speculative, this interpretation is supported by two kinds of evidence. First, different studies demonstrated that eye-related cues are spontaneously considered when acting with a partner (De Stefani, Innocenti, Secchi, Papa, & Gentilucci, 2013;Ferri et al, 2011;Innocenti et al, 2012;Quesque & Coello, 2014). Second, recent works have shown that humans may use others' pupil changes to produce adaptive responses, without any training, when explicitly informed about their importance (Naber, Stoll, Einhäuser, & Carter, 2013) but also spontaneously in the absence of any instruction (Brambilla, Biella, & Kret, 2018;Kret & de Dreu, 2017;Kret et al, 2015;Van Breen et al, 2018).…”