Author Type

Graduate Student

Date of Award

Spring 4-23-2026

Document Type

Thesis

Publication Status

Version of Record

Submission Date

May 2026

Department

Biological Sciences

College Granting Degree

Charles E. Schmidt College of Science

Department Granting Degree

Biological Sciences

Degree Name

Master of Science (MS)

Thesis/Dissertation Advisor [Chair]

Kate M. Detwiler

Abstract

Cooperative problem-solving tasks, including the loose-string paradigm, require individuals to coordinate their actions simultaneously to obtain a shared reward. These paradigms have been used extensively to assess social cognition, behavioral coordination, and partner preferences across taxa. Although the loose-string paradigm has been widely tested, it has not been applied to pair-bonded, monogamous primates such as owl monkeys (Aotus nancymaae), which exhibit affiliative behaviors including food sharing and bi-parental care. Investigating cooperation in this species may offer some clarification on whether more stable social bonds are associated with cooperative and cognitive task success as compared to those observed in larger social systems.

I asked two questions: (1) whether individuals would successfully complete the tasks, hypothesizing that bolder individuals would show greater problem-solving success, and (2) whether affiliation played a role in pairs cooperating successfully, hypothesizing that pairs displaying a higher affiliation would be better at coordination and higher success on the loose-string task. I assessed 20 captive adult owl monkeys across three assessments: habituation, an individual problem-solving task, and a cooperative task requiring simultaneous string-pulling.

To test the hypotheses, I fit a binomial generalized linear model predicting individual task success and a generalized linear model predicting participation. I also administered a personality survey to well established researchers, who ranked monkeys on behavioral traits using a 1–5 scale (5 = most likely). Survey data were summarized using a principal component analysis (PCA) biplot.

Females participated more than males across all task assessments. During the cooperative task, two pairs attempted the simultaneous string-pull task, but neither succeeded. No predictors showed strong statistical effects on participation or success, though proximity to social partner (p=0.06) and sex (females; p=0.07) showed marginal effects in the participation model for the individual task assessment. Despite limited cooperative success, consistent engagement during tasks suggests that coordination demands or task constraints, rather than motivation, limited cooperation; thus, alternative paradigms for owl monkeys may be warranted.

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