Revisiting Kindness and Confusion in Public Goods Experiments

There has been substantial recent interest in determining why there is cooperation in public goods experiments even in environments that provide all subjects with the incentive to free ride (see e.g., John O. Ledyard, 1995). Theories used to explain such cooperation generally posit either that subjects are “confused” in the sense that they make errors or do not understand the game’s incentives, or that subjects contribute due to social factors such as altruism and reciprocity. Although several authors have pointed out the importance of distinguishing between these alternatives, the roles that confusion and social motives play in determining public contributions remain poorly understood. This paper provides new evidence on the way that confusion and social motives determine contributions in public goods games by reporting data from experiments that use a new design with the Voluntary Contribution Mechanism (VCM). Two important and often replicated findings in the experimental public goods literature are (1) that subjects’ public contributions are much greater than predicted by standard economic theories of free-riding and (2) that these contributions decay over the course of multiple-round games (see e.g., Douglas D. Davis and Charles A. Holt, 1993). Models that employ social factors to explain cooperation and its decay usually assume that subjects are motivated by altruism, reciprocity, or fairness (see e.g., Andreoni, 1990; Rachel T. A. Croson, 1998; Anna Gunthorsdottir et al., 2001). It has been argued, for instance, that subjects make contributions in order to elicit like contributions from reciprocators in subsequent rounds and that decay in public contributions might result from “frustrated attempts at kindness” (Andreoni, 1995 p. 892). Specifically, because there is generally heterogeneity in the willingness to contribute to the public good, initially cooperative players will likely reduce their public contributions after being grouped with relatively low contributors. In contrast, confusion theories postulate that players make public contributions either in error or because they do not understand how to pursue their self-interest. These theories argue that high initial contributions decay primarily because subjects gradually come to understand the game’s incentives. Recently, Andreoni (1995) conducted an interesting series of experiments in the first and, to our knowledge, only effort to discriminate between these competing theories of cooperative play. He provides two reasons that doing this is important. The first is that knowing the relative importance of confusion and social motives in generating cooperative decay can provide a useful guide to future research. While Andreoni argues that such knowledge could be used to inform research on learning models, note also that to the extent confusion is found to be important, shedding light on the way different sorts of instructions affect confusion could help to improve pedagogics. A second compelling reason Andreoni gives is that the outcomes of experiments designed to test theories of social giving are difficult to interpret if confusion is a primary source of cooperation. * Houser: Department of Economics and Economic Science Laboratory, University of Arizona, Tucson, AZ 85721; Kurzban: Economic Science Laboratory, University of Arizona, Tucson, AZ 85721. We thank Mark Isaac, Kevin McCabe, David Porter, Vernon Smith, Bart Wilson, seminar participants at the University of Arizona, and two anonymous referees for valuable comments on this research. The authors gratefully acknowledge the research support of fellowships from the International Foundation for Research in Experimental Economics. This research was supported by Russell Sage Foundation Grant No. 98-00-01. The authors are responsible for any errors. 1 See, for example, James Andreoni (1995), Martin Sefton and Richard Steinberg (1996), and Thomas R. Palfrey and Jeffrey E. Prisbrey (1997). 2 This paper focuses on only standard linear games in which to contribute zero to the public good is the dominant strategy.