Auditory pre-experience modulates classification of affect intensity: evidence for the evaluation of call salience by a non-human mammal, the bat Megaderma lyra

Hanna B Kastein,Sabine Schmidt,Sripathi Kandula,Vinoth Ak Kumar

doi:10.1186/1742-9994-10-75

Hanna B Kastein, Sabine Schmidt + Show 2 more

Open Access

https://doi.org/10.1186/1742-9994-10-75

Copy DOI

Abstract

IntroductionImmediate responses towards emotional utterances in humans are determined by the acoustic structure and perceived relevance, i.e. salience, of the stimuli, and are controlled via a central feedback taking into account acoustic pre-experience. The present study explores whether the evaluation of stimulus salience in the acoustic communication of emotions is specifically human or has precursors in mammals. We created different pre-experiences by habituating bats (Megaderma lyra) to stimuli based on aggression, and response, calls from high or low intensity level agonistic interactions, respectively. Then we presented a test stimulus of opposite affect intensity of the same call type. We compared the modulation of response behaviour by affect intensity between the reciprocal experiments.ResultsFor aggression call stimuli, the bats responded to the dishabituation stimuli independent of affect intensity, emphasising the attention-grabbing function of this call type. For response call stimuli, the bats responded to a high affect intensity test stimulus after experiencing stimuli of low affect intensity, but transferred habituation to a low affect intensity test stimulus after experiencing stimuli of high affect intensity. This transfer of habituation was not due to over-habituation as the bats responded to a frequency-shifted control stimulus. A direct comparison confirmed the asymmetric response behaviour in the reciprocal experiments.ConclusionsThus, the present study provides not only evidence for a discrimination of affect intensity, but also for an evaluation of stimulus salience, suggesting that basic assessment mechanisms involved in the perception of emotion are an ancestral trait in mammals.

Highlights

Immediate responses towards emotional utterances in humans are determined by the acoustic structure and perceived relevance, i.e. salience, of the stimuli, and are controlled via a central feedback taking into account acoustic pre-experience
The bats responded to a high affect intensity test stimulus after experiencing stimuli of low affect intensity, but transferred habituation to a low affect intensity test stimulus after experiencing stimuli of high affect intensity
Conclusions: the present study provides evidence for a discrimination of affect intensity, and for an evaluation of stimulus salience, suggesting that basic assessment mechanisms involved in the perception of emotion are an ancestral trait in mammals

Summary

Introduction

Immediate responses towards emotional utterances in humans are determined by the acoustic structure and perceived relevance, i.e. salience, of the stimuli, and are controlled via a central feedback taking into account acoustic pre-experience. To perceive, and to show immediate responses to, In influencing-others scenarios, vocalisations expressing different emotions differ in their potential to disrupt the ongoing behaviour of a conspecific, and to re-direct its attention to assess the sound source. These distraction effects may serve as indicators of perceived emotion, validated by the behavioural display and changes in its intensity [18], in playback experiments. As stimulus structure and affect intensity are necessarily linked in situation-specific vocalisations, the above experiments cannot differentiate to what extent the behavioural response to a stimulus is directly shaped by its acoustic structure, or is modulated by assessment mechanisms of the brain that are dependent on preexperience, i.e. reflects the perceived emotion (for definition see [18])

Methods

Results

Discussion

Conclusion