Taking personality selection bias seriously in animal cognition research: a case study in capuchin monkeys (Sapajus apella)
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In most experimental work on animal cognition, researchers attempt to control for multiple interacting variables by training subjects prior to testing, allowing subjects to participate voluntarily, and providing subjects with food rewards. However, do such methods encourage selection bias from subjects’ personalities? In this study, we trained eighteen zoo-housed capuchin monkeys (Sapajus apella) for two experiments, under conditions of positive reinforcement (i.e. food rewards) and free-choice participation. Using a combination of behavioral and rater-based methods, we identified and validated five personality dimensions in these capuchins (Assertiveness, Openness, Neuroticism, Sociability, and Attentiveness). Scores on Openness were positively related to individual differences in monkey task participation, reflecting previous work showing that such individuals are often more active, curious, and willing to engage in testing. We also found a negative relationship between scores on Assertiveness and performance on tasks, which may reflect the trade-offs between speed and accuracy in these animals’ decision-making. Highly Assertive individuals (the most sociable within monkey groups) may also prioritize social interactions over engaging in research. Lastly, monkeys that consistently participated and performed well on both tasks showed significantly higher Openness and lower Assertiveness compared to others, mirroring relationships found between personality, participation, and performance among all participants. Participation and performance during training was clearly biased toward individuals with particular personalities (i.e. high Openness, low Assertiveness). Results are discussed in light of the need for careful interpretation of comparative data on animal cognition and the need for researchers to take personality selection bias more seriously.
KeywordsPlatyrrhines Temperament Cognitive experiment Selection bias Associative learning Training
This research would not have been possible without the many people involved in the capuchin personality study, particularly A. Weiss, S. Brosnan, and B. Thierry. F.B.M. would also like to personally thank Prof. Andrew Whiten, Director of Living Links (RZSS), who gave permission to conduct research there, and all of the Living Links/RZSS staff and students who kindly provided support and assistance. We also thank K. Howie who gave helpful statistical advice, P. Hancock who kindly conducted the bootstrapping analysis used in this study, the BERG (University of Stirling) for their feedback, and J. Anderson, S. Brosnan, and the anonymous reviewers for providing useful comments on earlier drafts. F.B.M gratefully acknowledges the Charles A. Lockwood Memorial Fund and the University of Stirling for funding. The authors declare that they have no conflict of interest.
- Bacon ES (1980) Curiosity in the American black bear. Bears: their biology and management, vol. 4, a selection of papers from the fourth international conference on bear research and management, Kalispell, Montana, USA, February 1977, pp 153–157Google Scholar
- Blaney PH, Millon T (2009) Oxford textbook of psychopathology. Oxford University Press, OxfordGoogle Scholar
- Carere C, Locurto C (2011) Interaction between animal personality and animal cognition. Curr Zool 57:491–498Google Scholar
- Deaner R, van Schaik C, Johnson V (2006) Do some taxa have better domain-general cognition than others? A meta-analysis of nonhuman primate studies. Evol Psychol 4:149–196Google Scholar
- Fragaszy DM, Visalberghi E, Fedigan LM (2004) The complete capuchin: the biology of the genus Cebus. Cambridge University Press, New YorkGoogle Scholar
- Morton FB, Lee PC, Buchanan-Smith HM, Brosnan S, Thierry B, Paukner A, de Waal FBM, Widness J, Essler J, Weiss A (2013) Personality structure in brown capuchin monkeys: comparisons with chimpanzees, orangutans, and rhesus macaques. J Comp Psychol. doi: 10.1037/a0031723
- Rehbein L, Moss MB (2002) Explorations of three modes of spatial cognition in the monkey. Psicológica 23:139–163Google Scholar
- Reid GMcG, Macdonald AA, Fidgett AL, Hiddinga B, Leus K (2008) Developing the research potential of zoos and aquaria. The EAZA research strategy EAZA executive office, Amsterdam. ISBN: 978-90-77879-10-8Google Scholar