Pre-SMA activation and the perception of contagiousness and authenticity in laughter sounds

Addison D.N Billing,Robert J Cooper,Sophie K Scott

doi:10.1016/j.cortex.2021.06.010

Abstract

Functional near-infrared spectroscopy and behavioural methods were used to examine the neural basis of the behavioural contagion and authenticity of laughter. We demonstrate that the processing of laughter sounds recruits networks previously shown to be related to empathy and auditory-motor mirror networks. Additionally, we found that the differences in the levels of activation in response to volitional and spontaneous laughter could predict an individual's perception of how contagious they found the laughter to be.

Highlights

Laughter is a very simple sound to produce and it is one of the earliest vocalisations that babies make (Addyman & Addyman, 2013; Scott et al, 2014)
After correcting for multiple comparisons, we found that localised activation in the pre-supplementary motor area (pre-supplementary motor area (SMA)) predicted the differences in both authenticity and contagion ratings for spontaneous laughter compared to volitional
We show that spontaneous laughter is rated as more contagious and authentic than volitional laughter, and that those differences in ratings are correlated with activity within the pre-SMA

Summary

Introduction

Laughter is a very simple sound to produce and it is one of the earliest vocalisations that babies make (Addyman & Addyman, 2013; Scott et al, 2014). Adults use laughter in a myriad of ways to convey meaning and express emotion in conversational interactions (Mazzocconi et al, 2020). Within a given social interaction, a listener needs to be able to judge the authenticity, as well as the emotional relevance, of those sounds. Laughter is an overwhelmingly social phenomenon; an individual is up to 30 times more likely to laugh when with others than when alone (Provine & Fischer, 1989). Laughter is a highly contagious behaviour: one of the most effective triggers cortex 1 4 3 ( 2 0 2 1 ) 5 7 e6 8 of laughter is another person's laughter (Hatfield et al, 1993; Hietanen et al, 1998; Mazzocconi et al, 2020; O'Nions et al, 2017; Provine, 1992; Wild et al, 2003). The simple presence of laughter can make a joke seem funnier, and this effect is even more significant if the laughter heard was spontaneous (Cai et al, 2019)

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Discussion

Conclusion