Chimpanzees' understanding of social leverage.

Alejandro Sánchez-Amaro,Shona Duguid,Josep Call,Michael Tomasello

doi:10.1371/journal.pone.0207868

Abstract

Social primates can influence others through the control of resources. For instance, dominant male chimpanzees might allow subordinates access to mate with females in exchange for social support. However, little is known about how chimpanzees strategically use a position of leverage to maximize their own benefits. We address this question by presenting dyads of captive chimpanzee (N = 6) with a task resulting in an unequal reward distribution. To gain the higher reward each individual should wait for their partner to act. In addition, one participant had leverage: access to an alternative secure reward. By varying the presence and value of the leverage we tested whether individuals used it strategically (e.g. by waiting longer for partners to act when they had leverage in the form of alternatives). Additionally, non-social controls served to show if chimpanzees understood the social dilemma. We measured the likelihood to choose the leverage and their latencies to act. The final decision made by the chimpanzees did not differ as a function of condition (test versus non-social control) or the value of the leverage, but they did wait longer to act when the leverage was smaller—particularly in test (versus non-social control) trials suggesting that they understood the conflict of interest involved. The chimpanzees thus recognized the existence of social leverage, but did not use it strategically to maximize their rewards.

Highlights

IntroductionA major source of power or leverage for the individual is access to alternatives [1, 2]
In bargaining with others, a major source of power or leverage for the individual is access to alternatives [1, 2]
Based on a previous study investigating the Chimpanzees’ understanding of social leverage strategies chimpanzees and five-year old children use to solve a conflict of interest [17], we presented chimpanzees with a task that always resulted in an unequal reward distribution

Summary

Introduction

A major source of power or leverage for the individual is access to alternatives [1, 2]. Access to alternatives means that the individual does not need the partner as much as the partner needs him and this creates an asymmetry of power independent of any pre-existing dominance relations. For instance, a buyer can persuade a vendor to lower prices if the buyer can acquire the same product at a lower price on the stall. The opposite can occur when the vendor is the only one that can provide the good. In this case the vendor can use this opportunity as bargaining leverage to raise prices.

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Results

Conclusion