Irrational choice behavior in human and nonhuman primates
Choice behavior in humans has motivated a large body of research with a focus on whether decisions can be considered to be rational. In general, humans prefer having choice, as do a number of other species that have been tested, even though having increased choice does not necessarily yield a positive outcome. Humans have been found to choose an option more often only because the opportunity to select it was diminishing, an example of a deviation from economic rationality. Here we extend this paradigm to nonhuman primates in an effort to understand the mechanisms underlying this finding. In this study, we presented two groups of laboratory monkeys, capuchins (Cebus apella) and rhesus macaques (Macaca mulatta), as well as human subjects, with a computerized task in which subjects were presented with two differently colored icons. When the subject selected an icon, differing numbers of food pellets were dispensed (or points were assigned), making each icon correspond to a certain level of risk (one icon yielded 1 or 4 pellets/points and the other yielded 2 or 3). Initially, both options remained constantly available and we established choice preference scores for each subject. Then, we assessed preference patterns once the options were not continuously available. Specifically, choosing one icon would cause the other to shrink in size on the screen and eventually disappear if never selected. Selecting it would restore it to its full size. As predicted, humans shifted their risk preferences in the diminishing options phase, choosing to click on both icons more equally in order to keep both options available. At the group level, capuchin monkeys showed this pattern as well, but there was a great deal of individual variability in both capuchins and macaques. The present work suggests that there is some degree of continuity between human and nonhuman primates in the desire to have choice simply for the sake of having choice.
KeywordsCapuchin monkeys Rhesus macaques Choice Risk Irrationality
We thank the researchers at the Language Research Center of Georgia State University for their assistance and support of this project. Portions were funded by the Professional Development Committee at Agnes Scott College, and research was approved by the Georgia State University Institutional Animal Care and Use Committee and Agnes Scott College Institutional Review Board. We also thank Tluang Cer and Martha Vorder Bruegge for assistance in data entry.
- Beran MJ, Klein ED, Evans TA, Antworth R, Chan B (2007) Perceived control, motivation, and task performance in capuchin monkeys. In: Zelick PR (ed) Issues in the psychology of motivation. Nova Science Publishers, Hauppauge, pp 171–185Google Scholar
- Evans TA, Beran MJ, Chan B, Klein ED, Menzel CR (2008) An efficient computerized testing method for the capuchin monkey (Cebus apella): adaptation of the LRC-CTS to a socially housed nonhuman primate species. Behav Res Methods 40(2):590–596. https://doi.org/10.3758/BRM.40.2.590 CrossRefPubMedGoogle Scholar
- Schwartz B (2004) The paradox of choice: why less is more. Ecco, New YorkGoogle Scholar