Social Evaluation Strategies of Chimpanzees in a Puzzle Box Task

Research Report by Stefanie Keupp & Esther Herrmann


The aim of our study was to investigate the social evaluation abilities of chimpanzees in the context of puzzle box tasks. We sought to understand how chimpanzees form impressions of their peers’ competence, and how these impressions influence their partner choice in competitive and cooperative settings.


We conducted our research at Ngamba Island Chimpanzee Sanctuary during two distinct periods: October to December 2022 and April to June 2023.

Puzzle Box Tasks:

– We presented chimpanzees with puzzle box tasks.

– The designated subject (focal chimp) observed two partners working on the puzzle boxes individually.

Cooperative Condition:

– In this setting, the subject and one partner worked jointly on a puzzle box.

– They could either collaborate for equal rewards or compete against each other.

Competitive Condition:

– In the competition test, the subject and a partner competed against each other, with the more competent individual having an advantage.


Cooperation Condition:

– We tested 11 chimpanzees in the cooperation test.

– The majority of chimpanzees preferred to work with a competent partner, demonstrating their ability to evaluate the competence of their peers.

– They made optimal partner choices based on observations made during the puzzle box task, indicating that they formed impressions of their peers’ abilities and used this information to make decisions.

Competition Condition:

– We tested 10 chimpanzees in the competition test.

– In contrast to the cooperation test, chimpanzees did not immediately transfer their knowledge from the observation phase.

– They learned to choose the incompetent partner as a competitor over time, suggesting that they learned to avoid partners against whom they repeatedly lost.


This research reveals fascinating insights into the social evaluation strategies of chimpanzees in the context of puzzle box tasks. It demonstrates that chimpanzees can form impressions of their peers’ abilities and use this information to optimize their choices in cooperation and competition.


We express our gratitude to the caregivers and staff at Ngamba Island Chimpanzee Sanctuary for their invaluable assistance during the research.

Note: The figures referenced in the report can be found in the original research document.

This research expands our understanding of the cognitive and social abilities of chimpanzees, shedding light on how they make decisions in complex social situations. It also highlights the importance of considering the cognitive abilities of non-human primates in various research contexts.

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