Personality and cognitive performance in western lowland gorillas (Gorilla gorilla)

Personality has been related to cognitive interest and performance in primates, including humans, yet this relationship remains unexplored in the genus Gorilla. In our study, we investigated the association between personality, interest, and performance in a cognitive enrichment task among 17 zoo-housed western lowland gorillas (Gorilla gorilla) from two zoos. We conducted personality assessments using the Gorilla Behavior Index questionnaire, which comprised 25 adjectives. Exploratory factor analysis using a Robust Unweighted Least Squares revealed six statistically significant factors with acceptable standards of interrater reliability and validity, accounting for 75% of the variance. The experimental task involved retrieving food from a tube presented in a social context. Each session consisted of a 30-minute recording of a gorilla performing the task, with a total of three sessions per individual. We included interest and success variables in the analysis. We used Generalized Linear Mixed Models to analyse each predictor variable. We found positive associations between Fearfulness and Extraversion and the variables of interest, but we did not find a link between the personality factors and task success. Additionally, we observed that repeated exposure to the task led to decreased interest but improved performance. Furthermore, females showed greater efficiency in food extraction over time compared to males. Thus, our findings suggest that personality and sex play an important role in explaining gorillas' interest and performance in solving cognitive enrichment tasks.