Abstract
Unlike many species, common marmosets (Callithrix jacchus), perhaps because they are cooperative breeders, appear to possess a personality domain that captures individual differences in directedness, focus, and perseverance, that resembles human Conscientiousness. However, one study of common marmosets personality did not find this domain. This difference between studies may have come about because, in the study that failed to find a Conscientiousness domain, many markers of that domain were excluded because of low interrater reliability. We increased the number of common marmosets that were rated, bringing it up to 128 from 77. We also gathered new data on subjective well-being and genetic data related to serotonin 1a receptor polymorphisms. Factor analysis revealed evidence for an Openness domain and a domain labeled “Impulsiveness” that combined low Conscientiousness and high emotional instability. The other domains included Sociability, Dominance, and Negative Affect, and resembled those found in previous studies of common marmosets. Correlations between these factors were higher than expected and a second-order factor analysis indicated the presence of a domain, Pro-Sociality, related to high Sociability, low Dominance, and low Impulsiveness, and a domain, Boldness, related to high Openness and low Negative Affect. Further analyses could not determine whether Pro-Sociality and Boldness were artifacts or represented a higher-level of personality organization. Statistically significant correlations were found between the domains and the subjective well-being measures. There were no statistically significant associations between personality and genotype of serotonin 1a receptor. New analytic methods and larger samples may help to better understand personality in common marmosets.
Competing Interest Statement
The authors have declared no competing interest.
Footnotes
We have no known conflicts of interest to declare.
This work was supported by AMED Grant Number JP20dm0307006 to TH, KAKENHI Grant Numbers 19H04904 and 20H00420 to MI-M, 18H05090 and18K06372 to CY. We wish to thank the Leading graduate program in Primatology and Wildlife Science. We are grateful to Hiromi Kobayashi for technical support and to Mr. Akihiro Kawasaki, Mr. Takashi Fukuoka, and Ms. Chiho Takeda for rating the animals. AW thanks Kyoto University for inviting him to be a Visiting Professor at the Wildlife Research Center.
The paper was submitted to the Journal of Comparative Psychology and it was rejected. One of the reviewers indicated that we failed to include some details in our methods. Other points of clarification and minor typos were pointed out, too. This revision takes all of those into account and reformats the references for another journal. Finally, I made some changes recommended by the authors. None of the changes relate to findings or analyses.