The Influence of the Relationship and Motivation on Inequity Aversion in Dogs
- 851 Downloads
One crucial element for the evolution of cooperation may be the sensitivity to others’ efforts and pay-offs in comparison with one’s own costs and gains. If an individual responds to a disadvantageous reward distribution, then it would likely increase its relative fitness compared with those who do not (Brosnan & de Waal, Nature 428:140, 2004). Recent experimental research indicates that sensitivity toward unequal reward distribution is not a uniquely human trait; non-human primates react to inequity if they witness a conspecific that obtains a more attractive reward for the same effort. However, primates are not the only species that cooperate and thus would benefit from inequity aversion. Canids also frequently cooperate with group members (e.g., wolves, wild dogs, etc.) or humans (domestic dogs), allowing for the possibility that they also are sensitive to the reward distribution. We report the findings of two studies of dogs’ responses to inequity and the social factors that mediate such responses. In the first study, we investigated whether domestic dogs showed a response to the inequity of rewards received for the same action in pairs of familiar dogs. We found that dogs showed significant behavioral differences when tested without food rewards when in the presence of a rewarded partner compared to the baseline and asocial control situations. This indicated that the presence of a rewarded partner matters (Range, Horn, Virányi, & Huber, Proc Natl Acad Sci USA 106(1):340–345, 2009). In contrast to primates, dogs did not react to differences in the quality of food or effort. In the second study, we analyzed whether individual (motivational or personality) characteristics determined the response of each subject to unequal reward distributions or whether the subject’s responses depended on the specific relationship they had with its partner. We found that individual motivation and the quality of the relationship influenced the dogs’ performance in test conditions, but that these factors varied across the control and reward inequity conditions. Overall, our results suggest that inequity aversion in dogs is conditional on their and their partner’s rewards. Whether inequity aversion is based on the same mechanisms in both humans and non-human primates is still unclear.
KeywordsInequity Motivation Canis familiaris Relationship quality
This study has received research funding from the European Community’s Sixth Framework Program under contract number: NEST 012929, the Austrian Science Fund (FWF) project P21244-B17, Stiftung Aktion Österreich—Ungarn 74öu3, Royal Canin Ltd., and Christian Palmers. The authors thank Lydia Hopper, Sarah Brosnan, and an anonymous referee for their useful comments on an earlier version of this manuscript, and all the dogs and their owners for participating in our experiment.
- Bekoff, M. (2004). Wild justice, cooperation and fair play: Minding manners, being nice, and feeling good. In R. Sussman & A. Chapman (Eds.), The origins and nature of sociality (pp. 53–79). Chicago: Aldine.Google Scholar
- Bräuer, J., & Hanus, D. (2012). Social Justice Research (forthcoming). Google Scholar
- Clark, M. S., & Grote, N. K. (2003). Close relationships. In T. Millon & M. J. Lerner (Eds.), Handbook of psychology: Personality and social psychology (Vol. 5, pp. 447–461). New York: Wiley.Google Scholar
- Clutton-Brock, J. (1995). Origins of the dogs: Domestication and early history. In J. A. Serpell (Ed.), The domestic dog: Its evolution, behaviour and interactions with people (pp. 199–216). Cambridge: Cambridge University Press.Google Scholar
- Coppinger, R., & Schneider, R. (1995). Evolution of working dogs. In J. A. Serpell (Ed.), The domestic dog: Its evolution, behaviour and interactions with people (pp. 21–47). Cambridge: Cambridge University Press.Google Scholar
- Drent, P. J., & Marchetti, C. (1999). Individuality, exploration and foraging in hand-raised juvenile great tits. In N. J. Adams & R. H. Slotow (Eds.), Proceedings of the 22nd international ornithological congress, Durban (pp. 896–914).Google Scholar
- Dugatkin, L. A. (Ed.). (1997). Cooperation among animals. Oxford series in ecology and evolution. Oxford: Oxford University Press.Google Scholar
- Freeman, H. D., & Gosling, S. D. (2010). Personality in nonhuman primates: A review and evaluation of past research. American Journal of Primatology, 71, 1–19.Google Scholar
- Horowitz, A. (2012). Fair is fine, but more is better: Limits to inequity aversion in the domestic dog. Social Justice Research, 25. doi: 10.1007/s11211-012-0158-7.
- Massen, J. J. M., van den Berg, L. M., Spruijt, B. M., & Sterck, E. H. M. (2011). Inequity aversion and the effect of relationship quality in long-tailed macaques (Macaca fascicularis). American Journal of Primatology. doi: 10.1002/ajp.21014.
- Mech, D. (1970). The wolf: The ecology and behaviour of an endangered species. Garden City, NY: Natural History Press.Google Scholar
- Mech, L. D., & Boitani, L. (2003). Wolf social ecology. In L. D. Mech & L. Boitani (Eds.), Wolves: Behavior, ecology, and conservation (pp. 1–35). Chicago: The University of Chicago Press.Google Scholar
- Pierce, J., & Bekoff, M. (2012). Wild justice redux: What we know about social justice in animals and why it matters. Social Justice Research, 25. doi: 10.1007/s11211-012-0154-y.
- Price, S. A., & Brosnan, S. F. (2012). To each according to his need? Variability in the responses to inequity in non-human primates. Social Justice Research, 25. doi: 10.1007/s11211-012-0153-z.
- Raihani, N. J., & McAuliffe, K. (2012). Does inequity aversion motivate punishment? Cleaner fish as a model system. Social Justice Research, 25. doi: 10.1007/s11211-012-0157-8.
- Scott, J. P., & Fuller, J. L. (1965). Genetics and the social behavior of the dog. Chicago: University of Chicago Press.Google Scholar
- van Hooff, J. A. R. A. M., & Wensing, J. A. B. (1987). Dominance and its behavioural measures in a captive wolf pack. In H. Frank (Ed.), Man and wolf (pp. 219–252). Dordrecht: Junk Publishers.Google Scholar
- Virányi, Zs., & Range, F. (submitted). Wolves understanding of human communicative cues in a two choice task.Google Scholar
- Yamamoto, S., & Takimoto, A. (2012). Social Justice Research (forthcoming). Google Scholar