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Access Type

Open Access Thesis

Document Type


Degree Program

Neuroscience & Behavior

Degree Type

Master of Science (M.S.)

Year Degree Awarded


Month Degree Awarded



Personality refers to multiple traits that are thought to be stable over time and across situations. It is recognized that personality has a neural basis and is associated with health outcomes. Whether personality is also associated with cognitive ability, however, is still a matter of intense debate. One way to examine these potential relationships is to use a nonhuman primate model for which complexities present in humans can be minimized. Recent research into the varying personality types of marmoset monkeys suggests that there are predominantly three to five core primary domains that most marmosets and other primates can be categorized into, such as dominance, sociability, and neuroticism. The aim of the proposed study was to categorize a small colony of marmosets into respective personality domains, and to examine correlations between the monkeys’ personalities and their cognitive ability. This study was be conducted on 27 marmoset monkeys (14 male, 13 female) housed in the Lacreuse lab at the University of Massachusetts Amherst. A personality survey based on Koski (2015) containing 55 personality traits was utilized by 8 human judges, all of whom have been working with these monkeys daily for at least one year. Each judge rated each individual monkey on each individual trait on a 1 to 7-point scale; 1 indicating total absence of a trait and 7 indicating extreme presence of a trait. Once the survey data was compiled, a principal component analysis (PCA) was conducted to condense the myriad of ratings into smaller distinguishable personality domains. Three personality types were identified in this population, consistent with other non-human primate species. An ICC(2) was performed to ensure the interrater reliabilities of the 8 judges were consistent enough to be considered. Lastly, a linear regression was conducted to reveal possible correlations between the observed personality domains and cognitive performance achieved in a reversal learning task. The results of this experiment showed no statistically significant relationships between any of the three personality domains: Assertiveness, Neuroticism, and Inquisitiveness with the reversal learning cognitive scores. Although these findings suggest that personality and cognitive flexibility are independent in marmosets, we cannot rule out that personality may influence other cognitive domains. Additional studies are needed to examine this possibility.


First Advisor

Agnes Lacreuse

Second Advisor

Melinda Novak

Third Advisor

Kirby Deater-Deckard