Abstract
Inequity aversion refers to an attempt to reduce a perceived discrepancy between one’s own input and output ratio (i.e. ratio between work invested and rewards obtained) and that of others. It has been proposed that inequity aversion might also play a role in the decision-making process of other animals. One issue, however, is that while studies in comparative cognition define clear behavioural criteria for an inequity aversion effect in animals, studies conducted on humans rely on an implicit definition of the concept involving assumptions for which there is yet no experimental evidence. In particular, the basis of inequity aversion is assumed to be a social comparison process that is further motivated by fairness concerns. Based on the studies on non-human animals, we tested whether inequity aversion in adult humans will satisfy the behavioural criteria for these assumptions. Although humans showed a decrease in working for a lower-value reward when working alone (non-social effect), this effect was enhanced when a partner was present (social effect) suggesting that their inequity aversion might be based on a social comparison process. Additionally, our tests ruled out the possibility that selfish motives underlie the subjects’ decisions, which raises the possibility that fairness concerns might have been the primary motive. Our results thus show that human behaviour satisfies two criteria imposed by the definition of inequity aversion. A similar pattern is shown in other species, suggesting that the same or similar processes might influence economic decision-making in both humans and non-human animals.
Similar content being viewed by others
References
Adams JS (1963) Toward an understanding of inequity. J Abnorm Soc Psych 67:422–436
Adams JS (1965) Inequity in social exchange. In: Berkowitz L (ed) Advances in experimental social psychology, vol 2. Academic Press, New York, pp 267–299
Andreoni J, Croson R (1988) Partners versus strangers: random rematching in public goods experiments. In: Plott CR, Smith VL (eds) Handbook of experimental economics results, vol 1. Elsevier, Amsterdam, pp 776–783
Blake PR, McAuliffe K (2011) I had so much it didn’t seem fair: eight-year-olds reject two forms of inequity. Cognition 120:215–224
Bolker BM, Brooks ME, Clark CJ, Geange SW, Poulsen JR, Stevens MHH, White JS (2009) Generalized linear mixed models: a practical guide for ecology and evolution. Trends Ecol Evol 24:127–135
Bolton GE, Ockenfels A (1997) A theory of equity, reciprocity and competition. Discussion paper, Pennsylvania State University
Bolton GE, Zwick R (1995) Anonymity versus punishment in ultimatum bargaining. Games Econ Behav 10:95–121
Bolton GE, Katok E, Zwick R (1998) Dictator game giving: rules of fairness versus acts of kindness. Int J Game Theory 27:169–299
Bräuer J, Call J, Tomasello M (2006) Are apes really inequity averse? Proc R Soc B 273:3123–3128
Brosnan SF (2006) Nonhuman species’ reactions to inequity and their implications for fairness. Soc Justice Res 19:153–185
Brosnan SF (2011) A hypothesis of the co-evolution of cooperation and responses to inequity. Front Neurosci 5:1–12
Brosnan SF, de Waal FBM (2003) Monkeys reject unequal pay. Nature 425:297–299
Brosnan SF, Schiff HC, de Waal FBM (2005) Tolerance for inequity may increase with social closeness in chimpanzees. Proc R Soc B 272:253–258
Brosnan SF, Freeman C, de Waal FBM (2006) Partner’s behaviour, not reward distribution, determines success in an unequal cooperative task in capuchin monkeys. Am J Primatol 68:713–724
Brosnan SF, Talbot C, Ahlgren M, Lambeth SP, Schapiro SJ (2010) Mechanisms underlying responses to inequitable outcomes in chimpanzees, Pan troglodytes. Anim Behav 79:1229–1237
Burkart JM, Fehr E, Efferson C, van Schaik CP (2007) Other-regarding preferences in a non-human primate: common marmosets provision food altruistically. Proc Natl Acad Sci 104:19762–19766
Camerer C, Thaler R (1995) Ultimatums, dictators, and manners. J Econ Perspect 9:209–219
Cheke LG, Loissel E, Clayton NS (2012) How do children solve the Aesop’s fable? PLoS ONE 7:e40574. doi:10.1371/journal.pone.0040574
Cooper R, DeJong DV, Forsythe R (1996) Cooperation without reputation: experimental evidence from prisoner’s dilemma games. Game Econ Behav 12:187–218
Croson RTA (1996) Partners and strangers revisited. Econ Lett 53:25–32
Dana J, Cain DM, Dawes RM (2006) What you don’t know won’t hurt me: costly (but quiet) exit in dictator games. Organ Behav Hum Dec 100:193–201
de Wit S, Dickinson A (2009) Associative theories of goal-directed behaviour: a case for animal–human translational models. Psychol Res 73:463–476
Dindo M, de Waal FBM (2007) Partner effects on food consumption in brown capuchin monkeys. Am J Primatol 69:448–456
Dubreuil D, Gentile MS, Visalberghi E (2006) Are capuchin monkeys (Cebus apella) inequity averse? Proc R Soc B 273:1223–1228
Engelman D, Fischbacher U (2009) Indirect reciprocity and strategic reputation building in an experimental game. Game Econ Behav 67:399–407
Fehr E, Fischbacher U (2004) Social norms and human cooperation. Trends Cogn Sci 8:185–190
Fehr E, Schmidt KM (1999) A theory of fairness, competition, and cooperation. Q J Econ 114:817–868
Fontenot MB, Watson SL, Roberts KA, Miller RW (2007) Effects of food preferences on token exchange and behavioural responses to inequality in tufted capuchin monkeys, Cebus apella. Anim Behav 74:487–496
Frank RH (2001) Cooperation through emotional commitment. In: Nesse RM (ed) Evolution and the capacity for commitment. Russell Sage Foundation, New York, pp 57–76
Greenberg J (1989) Cognitive reevaluation of outcomes in response to underpayment inequity. Acad Manage J 32:174–184
Griskevicius V, Tybur JM, Sundie JM, Cialdini RB, Miller GE, Kenrick DT (2007) Blatant benevolence and conspicuous consumption: when romantic motives elicit strategic costly signals. J Pers Soc Psychol 93:85–102
Güth W, Schmittberger R, Tietz R (1990) Ultimatum bargaining behavior—a survey and comparison of experimental results. J Econ Psychol 9:417–449
Hachiga Y, Silberberg A, Parker S, Sakagami T (2009) Humans (Homo sapiens) fail to show an inequity effect in an ‘up-linkage’ analog of the monkey inequity test. Anim Cogn 12:359–367
Henrich J (2004) Inequity aversion in capuchins? Nature 428:139
Henrich J, Boyd R, Bowles S, Camerer C, Fehr E, Gintis H, McElreath R (2001) In search of homo economicus: behavioral experiments in 15 small-scale societies. Am Econ Rev 91:73–78
Kogut T (2012) Knowing what I should, doing what I want: from selfishness to inequity aversion in young children’s sharing behaviour. J Econ Psychol 33:226–236
Kreps DW, Wilson R (1982) Reputation and imperfect information. J Econ Theory 27:253–279
Lawler EE III, O’Gara PW (1967) Effects of inequity produced by underpayment on work output, work quality, and attitudes toward the work. J Appl Psychol 51:403–410
Levine DK (1998) Modeling altruism and spitefulness in experiments. Rev Econ Dynam 1:593–622
Massen JJM, van de Berg LM, Spruijt BM, Sterck EHM (2012) Inequity aversion in relation to effort and relationship quality in long-tailed Macaques (Macaca fascicularis). Am J Primatol 74:145–156
Neiworth JJ, Johnson ET, Whillock K, Greenberg J, Brown V (2009) Is a sense of inequity an ancestral primate trait? Testing social inequity in cotton top tamarins (Saguinus oedipus). J Comp Psychol 123:10–17
Pritchard RB, Dunnette MD, Jorgenson DO (1972) Effects of perceptions of equity and inequity on worker performance and satisfaction. J Appl Psychol 56:75–94
Rabin M (1993) Incorporating fairness into game theory and economics. Am Econ Rev 83:1231–1302
Range F, Horn L, Virányi Z, Huber L (2009) The absence of reward induces inequity aversion in dogs. Proc Natl Acad Sci 106:340–345
Schall ROBE (1991) Estimation in generalized linear models with random effects. Biometrika 78:719–727
Stevens JR (2010) Donor payoffs and other-regarding preferences in cotton-top tamarins (Saguinus oedipus). Anim Cogn 13:663–670
Takimoto A, Kuroshima H, Fujita K (2010) Capuchin monkeys (Cebus apella) are sensitive to others’ rewards: an experimental analysis of food-choice for conspecifics. Anim Cogn 13:249–261
Talbot CF, Freeman HD, Williams LE, Brosnan SF (2011) Squirrel monkey’s response to inequitable outcomes indicates a behavioural convergence within the primates. Biol Lett 7:680–682
Weick EK, Nesset B (1968) Preferences among forms of equity. Organ Behav Hum Perf 2:400–416
Wynne CDL (2004) Fair refusal by capuchin monkeys. Nature 428:140
Yamagishi T, Horita Y, Takagishi H, Shinada M, Tanida S, Cook KS (2009) The private rejection of unfair offers and emotional commitment. PNAS 106:11520–11523
Zizzo DJ (2003) Money burning and rank egalitariarnism with random dictators. Econ Lett 81:283–366
Zizzo DJ, Oswald A (2001) Are people willing to pay to reduce others’ incomes? Annales d’economie et de statistique 63(64):39–65
Zuur A, Ieno EN, Walker N, Saveliev AA, Smith GM (2009) Mixed effects models and extensions in ecology with R. Springer, New York
Acknowledgments
This research was funded by the University of Cambridge. We thank Yichao Yu for programming the task, Joanne Shahvisi and Emily Curtis-Harper for help in conducting the experiments, Rachael Shaw for help with running the analyses and Lucy Cheke and James Thom for comments on an earlier draft of the manuscript.
Conflict of interest
The authors declare that they have no conflict of interest.
Author information
Authors and Affiliations
Corresponding author
Additional information
This research has been approved by the Cambridge Psychology Research Ethics Committee, University of Cambridge.
Electronic supplementary material
Below is the link to the electronic supplementary material.
Rights and permissions
About this article
Cite this article
Ostojić, L., Clayton, N.S. Inequity aversion in human adults: testing behavioural criteria from comparative cognition. Anim Cogn 16, 765–772 (2013). https://doi.org/10.1007/s10071-013-0610-6
Received:
Revised:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s10071-013-0610-6