Modulating Mimetic Preference with Theta Burst Stimulation of the Inferior Parietal Cortex.

Luca F Ticini,Sonja A Kotz,Cosimo Urgesi

doi:10.3389/fpsyg.2017.02101

Abstract

We like an object more when we see someone else reaching for it. To what extent is action observation causally linked to object valuation? In this study, we set out to answer to this question by applying continuous theta burst stimulation (cTBS) over the left inferior parietal lobule (IPL). Previous studies pointed to this region as critical in the representation of others' actions and in tool manipulation. However, it is unclear to what extent IPL's involvement simply reflects action observation, rather than a casual role in objects' valuation. To clarify this issue, we measured cTBS-dependent modulations of participants' “mimetic preference ratings”, i.e., the difference between the ratings of pairs of familiar objects that were (vs. were not) reached out for by other individuals. Our result shows that cTBS increased mimetic preference ratings for tools, when compared to a control condition without stimulation. This effect was selective for items that were reached for or manipulated by another individual, whilst it was not detected in non-tool objects. Although preliminary, this finding suggests that the automatic and covert simulation of an observed action, even when there is no intention to act on an object, influences explicit affective judgments for objects. This work supports embodied cognition theories by substantiating that our subjective preference is grounded in action.

Highlights

In the last decades, research has shown that people commonly prefer objects that are the goal of others’ actions, regardless of the objects’ actual value(s) or their intrinsic properties (Gollwitzer and Moskowitz, 1996)
A functional neuroimaging study (Lebreton et al, 2012), designed to uncover the neural mechanisms of this phenomenon, surprisingly found that object preference is influenced by the activity of motor-related areas, namely the ventral premotor and the inferior parietal cortices, belonging to the action observation–action execution network
As far as the Non-tools category is concerned, we found a significant main effect of “Action” [F(1, 11) = 8.48, p = 0.014, η2p = 0.43] confirming that in both continuous theta burst stimulation (cTBS) and Non-cTBS conditions Goalobjects were preferred more than NoGoal-objects

Summary

Introduction

Research has shown that people commonly prefer objects that are the goal of others’ actions, regardless of the objects’ actual value(s) or their intrinsic properties (Gollwitzer and Moskowitz, 1996). On the playground children run after the same toy even when similar toys are readily available In social cognition, this behavior has been termed mimetic desire (Girard, 1988) and it is recognized as a case of goal contagion (Aarts et al, 2004), for which objects that are the target of another individual tend to become the goal for the observer. The authors found that during the observation of goal-directed actions the activity of these parietofrontal areas modulated that of the ventral valuation system where the perceived value of objects is encoded (Rangel et al, 2008; Chib et al, 2009; Lebreton et al, 2009; Peters and Büchel, 2010). The present experiment represents a preliminary approach aimed at deciding between these two alternatives

Methods

Results

Conclusion