The role of perspective in discriminating between social and non-social intentions from reach-to-grasp kinematics

Abstract

Making correct inferences regarding social and individual intentions may be crucial for successful interactions, especially when we are required to discriminate between cooperative and competitive behaviors. The results of previous studies indicate that reach-to-grasp kinematic parameters may be used to infer the social or individual outcome of a movement. However, the majority of the studies investigated this ability by presenting reach-to-grasp movements from a third-person perspective only. The aim of the present study was to assess whether the ability to recognize the intent associated to a reach-to-grasp movement varies as a function of perspective by manipulating the perspective of observation (second- and third-perspective) within participants. To this end, we presented participants with video clips of models performing a reach-to-grasp movement with different intents. The video clips were recorded both from a lateral view (third-person perspective) and from a frontal view (second-person perspective). After viewing the clips, in two subsequent tasks participants were asked to distinguish between social and non-social intentions by observing the initial phase of the same action recorded from the two different views. Results showed that, when a fast-speed movement was presented from a lateral view, participants were able to predict its social intention. In contrast, when the same movement was observed from a frontal view, performance was impaired. These results indicate that the ability to detect social intentions from motor cues can be biased by the visual perspective of the observer, specifically for fast-speed movements.

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

“…Both interpretations would be congruent with spontaneous motor simulation frameworks (Gallese & Goldman, 1998;Rizzolatti & Craighero, 2004), recruiting their own motor system to interpret other's intention, participants would experience the drive for a consecutive action in the case of personal intention. A reversed pattern may however be expected when shifting from a third to a second person perspective (see Ciardo et al, 2017), in which the socially oriented actions of others could trigger the motor preparation of complementary response in the observer (e.g. Quesque et al, 2015).…”

“…Our aims and predictions are threefold. First, we investigate whether people can categorize social intentions from the kinematics of arm movements only, as is predicted based on previous literature (Ciardo et al, 2017;Lewkowicz et al, 2015;Sartori et al, 2011). Second, we predict that participants' pupils differentiate between the personal and social intentions endorsed by the actors in the video clips.…”

“…The research described above demonstrates that body language occupies an important role in human social interaction (de Gelder et al, 2010;Van den Stock, Hortensius, Sinke, Goebel, & De Gelder, 2015) and accumulating evidence suggests that naïve observers are able to discriminate subtle body cues to anticipate others' intentions (Ciardo et al, 2017;Koul et al, 2019;Lewkowicz et al, 2015;Sartori et al, 2011;Stapel et al, 2012; see also Cavallo, Koul, Ansuini, Capozzi, & Becchio, 2016 for evidences from a modelling approach). In order to anticipate others' goals, humans integrate information from the others' body movements and eye signals (Flanagan, Rotman, Reichelt, & Johansson, 2013;Rotman, Troje, Johansson, & Flanagan, 2006).…”

“…when passing an object to a partner), participants tend to unconsciously exaggerate the temporal (Ferri, Campione, Dalla Volta, Gianelli, & Gentilucci, 2010;Quesque & Coello, 2014;Quesque, Lewkowicz, Delevoye-Turrell, & Coello, 2013;Quesque, Mignon, & Coello, 2017;Straulino, Scaravilli, & Castiello, 2016) as well as the spatial (Becchio, Sartori, Bulgheroni, & Castiello, 2008;Quesque & Coello, 2014;Quesque et al, 2013Quesque et al, , 2015Quesque et al, , 2017 parameters of their actions, compared to actions performed with a personal intention (that is, when others are not relevant for the accurate completion of the goal). Converging evidence suggests that these motor deviances, even if small, can be used by observers to understand the intentions that drive others' actions (Ciardo, Campanini, Merlo, Rubichi, & Iani, 2017;Lewkowicz, Quesque, Coello, & Delevoye-Turrell, 2015;Sartori, Becchio, & Castiello, 2011;Stapel, Hunnius, & Bekkering, 2012), especially when the contextual information is ambiguous (Koul, Soriano, Tversky, Becchio, & Cavallo, 2019). Some findings even support that they may spontaneously lead to the preparation of adaptive motor responses in the case of social intentions (Quesque et al, 2015).…”

Response coordination emerges in cooperative but not competitive joint task

“…Cooperation and competition are social relations that rely on opposite goal interdependency (Deutsch 2011), and differently affect social cognitive processes, as joint attention (e.g., Ciardo, Ricciardelli, Lugli, Rubichi, and Iani, 2015), sensorimotor synchronization (e.g., Fairhurst, Janata, and Keller, 2012), and reach-to-grasp kinematics (e.g. Ciardo, Campanini, Merlo, Rubichi, and Iani, 2017). When we cooperate with someone, our goals are positively related.…”