Listeners\u2019 perceptions of the\xa0certainty and honesty of a speaker are associated with a common prosodic signature

Louise Goupil,Gabriel Reyes,Emmanuel Ponsot,Jean-Julien Aucouturier,Daniel Richardson

doi:10.1038/s41467-020-20649-4

Abstract

The success of human cooperation crucially depends on mechanisms enabling individuals to detect unreliability in their conspecifics. Yet, how such epistemic vigilance is achieved from naturalistic sensory inputs remains unclear. Here we show that listeners’ perceptions of the certainty and honesty of other speakers from their speech are based on a common prosodic signature. Using a data-driven method, we separately decode the prosodic features driving listeners’ perceptions of a speaker’s certainty and honesty across pitch, duration and loudness. We find that these two kinds of judgments rely on a common prosodic signature that is perceived independently from individuals’ conceptual knowledge and native language. Finally, we show that listeners extract this prosodic signature automatically, and that this impacts the way they memorize spoken words. These findings shed light on a unique auditory adaptation that enables human listeners to quickly detect and react to unreliability during linguistic interactions.

Highlights

The success of human cooperation crucially depends on mechanisms enabling individuals to detect unreliability in their conspecifics
Acoustic analysis of these recordings is performed, and listeners are asked to recover the degree of certainty expressed by the speakers. Acoustic analyses of these recordings typically reveal that speakers’ uncertainty is associated with decreased volume and rising intonation[9,13,14,18], and to a lesser extent higher[14] mean pitch as well as slower[13,14,16,19] speech rate. While these studies show that listeners are able to infer speakers’ uncertainty from the sound of their voice[13,14,16,19,20], the precise perceptual representations used by listeners to perform these judgments remain unclear
Despite the fact that both tasks were separated by an interval of 1 week, and the large variety of random tokens presented to the listeners, we found that the perceptual representations obtained for honesty and certainty were strikingly similar for all three acoustic dimensions (Fig. 1a)

Summary

Introduction

The success of human cooperation crucially depends on mechanisms enabling individuals to detect unreliability in their conspecifics. While these studies show that listeners are able to infer speakers’ uncertainty from the sound of their voice[13,14,16,19,20], the precise perceptual representations used by listeners to perform these judgments remain unclear Because these prosodic signatures are typically examined in procedures where speakers deliberately produce them, it is unknown whether, at a fundamental level, they are inherently communicative (i.e., natural or conventional signals)[21,22] as opposed to constituting natural signs[22], e.g., of cognitive effort[18,19,23] (throughout the paper, we use “natural” by opposition with “conventional” to refer to meaning that relies on intrinsic and recurrent associations, rather than arbitrary, culturally learned conventions[24,25]). There are important differences between portrayed and spontaneous prosodic displays[28]: actors’ productions may reflect stereotypical rather than veridical expressions, and in addition, they may not be aware of all the prosodic signatures that are naturally produced and used by listeners to perceive honesty and certainty

Methods

Results

Conclusion