Dogs\u2019 reaction to inequity is affected by inhibitory control

Désirée Brucks,Sarah Marshall-Pescini,Friederike Range

doi:10.1038/s41598-017-16087-w

Désirée Brucks, Sarah Marshall-Pescini + Show 1 more

Open Access

https://doi.org/10.1038/s41598-017-16087-w

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Abstract

Inequity aversion is thought to act as a mechanism to ensure cooperation and has been studied in many different species, consistently revealing inter-individual variation. Inhibitory control has been proposed to act as one factor responsible for this variation since individuals need to inhibit performing the required action and/or refuse rewards in order to exhibit inequity aversion. Here, we investigated if dogs’ sensitivity to inequity is affected by their capacity for inhibitory control, assessed in a test battery and questionnaire. Overall, dogs showing high compulsivity scores (i.e. repetitive behaviours independent of feedback) were more motivated to participate in the inequity task independent of the rewarding scheme. Dogs were more sensitive to inequity and individual contrast if they exhibited a slower decision speed in the inhibition tasks. Furthermore, less persistent and more impulsive dogs were more sensitive to reward inequity, potentially due to having a lower tolerance level for frustration. Results indicate that aspects of inhibitory control can explain the variation in dogs’ inequity response, highlighting one of the mechanisms underlying responses to inequity. Emphasising the importance to design paradigms, which allow us to disentangle capacities to recognise inequity from the inability to react to it due to poor inhibitory control abilities.

Highlights

Cooperation with other individuals in order to achieve a goal that could not be reached alone seems to be clearly advantageous
Capuchins monkeys were found to exhibit better inhibition in a detour-reaching task than tamarins and authors related these findings to results from inequity aversion studies showing that while capuchins do show inequity aversion, tamarins do not react to unequal treatment[19]
We found a significant negative interaction between the decision speed component and the food control as well as the reward inequity condition, while this interaction was only a trend for the quality inequity condition

Summary

Introduction

Cooperation with other individuals in order to achieve a goal that could not be reached alone seems to be clearly advantageous. Inequity aversion has been assessed by requiring pairs of individuals to alternately perform an action (e.g. exchanging a token, giving a paw or pulling a tray) in order to receive rewards, which are either or unequally distributed between partners. Individual characteristics, such as age[17], sex[10,15] (but see ref.18), and certain aspects of personality[12] seem to play a role in the response to unequal treatment Another factor that has consistently been suggested to influence an individual’s reaction to inequity is inhibitory control (e.g. refs[19,20]). In order to show an aversion to inequity, an animal needs to inhibit delivering a token, pulling a tray or giving the paw, despite having been consistently rewarded for carrying out this action or refuse to take a food reward of lesser quality than the partner. Lakshminaryanan and Santos did not obtain measurements of inequity aversion from the same monkeys that were tested in the inhibitory control task and the authors could only make inferences about a possible relationship between these factors without having the actual data from both inequity and inhibition task to test this hypothesis directly

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