Human infants detect other people's interactions based on complex patterns of kinematic information.

Martyna A Galazka,Pär Nyström,Terje Falck-Ytter,Laëtitia Roché,Maurice Ptito

doi:10.1371/journal.pone.0112432

Martyna A Galazka, Pär Nyström + Show 3 more

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https://doi.org/10.1371/journal.pone.0112432

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Abstract

Do infants perceive other people's interactions by means of a mechanism that integrates biological motion information across the observed individuals? In support of this view, the present study demonstrates that infants (N = 28, Age = 14 months) discriminate between point light displays representing disrupted and non-disrupted interactions between people, even though the two interaction types are identical at the level of individual point light agents. Moreover, a second experiment (sample 2: N = 28, Age = 14 months) indicated that visual preference in this context is influenced by an audiovisual integration processes that takes into account the presence of an interaction between people. All these results were found exclusively for upright displays – when stimuli were shown upside-down (disrupting biological motion processing), performance was random. Collectively, these findings point to an important role for biological motion in social perception in human infants.

Highlights

The ability to identify biological motion – the distinct, non-rigid movement patterns produced by humans or animals – is believed to serve important evolutionary purposes, including detection of predators and filial attachment
Looking at the screen areas of interest (AOIs) was similar in the two conditions (M = 7.00 seconds, SD = 1.33 in the Upright orientation and M = 7.02 seconds, SD = 1.38 in the Inverted orientation)
These results suggest that adding the auditory stimulus eliminated the preference for the non-disrupted pair seen in Study 1

Summary

Introduction

The ability to identify biological motion – the distinct, non-rigid movement patterns produced by humans or animals – is believed to serve important evolutionary purposes, including detection of predators and filial attachment. Neri, Luu, and Levi (2006) [10] presented adults with point-light displays of two agents that were either dancing or fighting In these interactions, the actions of one agent clearly constrain the actions of the other agent. When judging whether one or two agents were present, participants were most accurate when meaningful, synchronized interactions were shown, despite the fact that even the desynchronized displays contained two agents. The authors interpreted this finding as reflecting implicit knowledge about human interactions and the effects one agent’s actions have on the other agent’s actions. Manera et al (2011) extended Neri et al.’s findings, suggesting that even without any physical contact between agents, the gestures of one agent enhanced visual perception of the other agent’s biological motion

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