Qualitative and Quantitative Value Assessments of Food Rewards by Brown Capuchin Monkeys (Cebus apella) Open Access

Abstract

The brown capuchin (Cebus apella) relies on extractive foraging behaviors to effectively exploit a wide range of ecological substrates for nutritional gain. The Extractive Foraging Hypothesis theorizes that these behaviors developed as a result of the increasing cognitive capabilities that coincide with increases in primate brain size. In turn these behaviors have provided the capuchin with a means of offsetting the energetic costs of evolving and maintaining such a large brain. This link between the complexities of foraging behavior and enhanced cognition is the focus of the present study.

The behavioral flexibility of the brown capuchin in making foraging choices was empirically tested, following a token-exchange paradigm well documented in the literature. A subsequent methodology of direct food choice was then introduced to flesh out the results of the token-exchange tests. Results suggest that brown capuchins fail to simultaneously consider both qualitative and quantitative differences between binary options at significant levels. Failure to exhibit high behavioral flexibility pertaining to relative food value assessment weakens either the foundation of the Extractive Foraging Hypothesis or the argument for co-selection between large brains and cognitive capacities, such as judgment of quality and quantity. Still, further value assessment research on the brown capuchin and other primate species is needed to confirm these findings.

Table of Contents

Table of Contents

Introduction………………………………………………………………………………….......…....1

Methods………………………………………………………………………………………...........…10

Figure 1: Tokens………………................…………………………………………..........13

Table 1: Token Value Assignments………………………………………………….........16

Table 2: Pair Choice Test Sequence...…………………………….……………..........18

Results…………………………………………………………………………………………..…........18

Figure 2: Quality and Quantity Food Preference Controls…..……….......…..19

Figure 3: Initial Token Preference Control…..………….…………………….......…..20

Figure 4: Token Pairs-Quality Tests………..…….........……………………..........21

Figure 5: Token Pairs-Quantity Tests 3A vs. 1A..……...……………….......…..22

Figure 6: Token Pairs-Quantity Tests 1C vs. 3C.....…………………….......…..22

Figure 7: Token Pairs-Composite Tests………………..…………...………........…..23

Figure 8: Food Pairs-Quality Tests……………………………………....……….......….25

Figure 9: Food Pairs-Quantity Tests………………..………………………………........25

Figure 10: Food Pairs-Composite Tests……………………………………………........26

Figure 11: Interaction between Quality and Quantity (Quality Series)..….27

Figure 12: Interaction between Quality and Quantity (Quantity Series).…28

Discussion………………………………………………………………………………………...........28

References…………………………………………………………………………………….........….34

About this Honors Thesis

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School	Emory College
Department	Anthropology
Degree	BS
Submission	Honors Thesis
Language	English
Research Field	Psychology, Psychobiology Anthropology, Physical Psychology, Cognitive
Keyword	quality quantity token exchange value brown capuchin
Committee Chair / Thesis Advisor	Gouzoules, Sarah, Emory University
Committee Members	De Waal, Frans B M, Emory University Parr, Lisa, Emory University Stout, Dietrich, Emory University

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