Partner Coordination in Relation to Reward Cost on a Computerized Task in a Social Group of Rhesus Monkeys (Macaca mulatta) Open Access

Roberts, Rebecca (Fall 2019)

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We manipulated how monkeys were rewarded at two interconnected touch-screen computer kiosks continuously available in their home enclosure to provide less expensive rewards (FR1) when two monkeys participated together at the kiosks and more expensive (FR10), or no, rewards when monkeys participated alone. Our goal was to determine if rhesus monkeys can learn the contingency between a partner’s participation at an adjacent kiosk and reward outcome. We examined whether monkeys’ partnered behavior (two monkeys working at the kiosks) increased when partnered trials, where two monkeys were logged-in and working at the kiosks at the same time, were rewarded on FR1, and solo trials, where only one monkey was logged-in and working, were rewarded on FR10 or not at all. We also examined how the monkeys engaged in partnered behavior during these conditions to determine the extent to which they learned the contingency. 14 young rhesus monkeys were given voluntary access to the computer kiosks and freedom of partner choice.  Monkeys significantly increased partnered behavior during conditions when partnered trials produced less expensive rewards than conditions when partnered and solo trial rewards did not differ. Certain types of partnered behavior, such as participating at the kiosks within close temporal proximity of a partner after refraining from solo participation, were also significantly higher when partnered trials were less expensive. Rhesus monkeys are able to learn the contingency between a partner’s participation and reward outcome, and actively adjust their behavior to maximize rewards using this contingency.  

Table of Contents

Introduction                                                                                                                       1

   Defining and Assessing Cooperation                                                                          2

   Cooperation in Rhesus Monkeys                                                                                  8

   Current Study                                                                                                                  12

Methods                                                                                                                               15

   Study Design Overview                                                                                                 15

   Subjects                                                                                                                            16

   RfID Tag Implantation                                                                                                  17

   Apparatus and Materials                                                                                               17

   Apparatus Exploration                                                                                                     19

   Data Collection Timeline                                                                                                 19

   Experimental Design                                                                                                        19

       Software overview                                                                                                        19

       Kiosk training                                                                                                             20

       Fixed-ratio reward training                                                                                          21

       Partner coordination                                                                                                   22

           Condition 1                                                                                                                24       

           Condition 2                                                                                                                24

           Condition 3                                                                                                                25

           Condition 4                                                                                                                26

           Condition 5                                                                                                                27

           Condition 6                                                                                                                27

           Condition 7                                                                                                                28

  Data Extraction and Analysis                                                                                           28

Results                                                                                                                                 32

   Overall Descriptive Data                                                                                                 32

   Condition Effects                                                                                                            32

       Mean trial types across conditions (Appendix)                                                           32       

       Proportion of partnered trials                                                                                      33

       Proportion of partnered trials with dual activation                                                       35

       Proportion of partnered trials without dual activation                                                 37

       Partnered bouts                                                                                                            38

       Partnered bouts with dual activation                                                                           39

       Partnered bouts without dual activation                                                                      41    

       Average solo trials completed prior to partnered bouts without dual activation           42

       Proportion of solo bouts that end in partnered trials                                         45

       Duration of partnered bouts                                                                                     46

       Duration of partnered bouts with dual activation                                               47

       Duration of partnered bouts without dual activation                                          48

       Removing the secondary color cue                                                                          48

       Performance by individual                                                                                         49

       Dyads                                                                                                                           50

Discussion                                                                                                                            51

References                                                                                                                           69

Tables                                                                                                                                    73

Figures                                                                                                                       75

Appendix                                                                                                                              95

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