Commentators agree that the Perception and Attention Deficit (PAD) model is a promising model for accounting for recurrent complex visual hallucinations (RCVH) across several disorders, though with varying detailed criticisms. Its central tenets are not modified, but further consideration of generative models of visual processing and the relationship of proto-objects and memory systems allows the PAD model to deal with variations in phenomenology. The commentaries suggest new ways to generate evidence that will test the model.

Researchers from across the social sciences have found consistent deviations from the predictions of the canonical model of self-interest in hundreds of experiments from around the world. This research, however, cannot determine whether the uniformity results from universal patterns of human behavior or from the limited cultural variation available among the university students used in virtually all prior experimental work. To address this, we undertook a cross-cultural study of behavior in ultimatum, public goods, and dictator games in a range of small-scale societies exhibiting a wide variety of economic and cultural conditions. We found, first, that the canonical model – based on self-interest – fails in all of the societies studied. Second, our data reveal substantially more behavioral variability across social groups than has been found in previous research. Third, group-level differences in economic organization and the structure of social interactions explain a substantial portion of the behavioral variation across societies: the higher the degree of market integration and the higher the payoffs to cooperation in everyday life, the greater the level of prosociality expressed in experimental games. Fourth, the available individual-level economic and demographic variables do not consistently explain game behavior, either within or across groups. Fifth, in many cases experimental play appears to reflect the common interactional patterns of everyday life.

Canonical utility theory may have adopted its selfishness postulate because it lacked theoretical rationales for two major kinds of incentive: empathic utility and self-signaling. Empathy – using vicarious experiences to occasion your emotions – gives these experiences market value as a means of avoiding the staleness of self-generated emotion. Self-signaling is inevitable in anyone trying to overcome a perceived character flaw. Hyperbolic discounting of future reward supplies incentive mechanisms for both empathic utility and self-signaling. Neither can be effectively suppressed for an experimental game.

The target article by Henrich et al. describes some economic experiments carried out in fifteen small-scale societies. The results are broadly supportive of an approach to understanding social norms that is commonplace among game theorists. It is therefore perverse that the rhetorical part of the paper should be devoted largely to claiming that “economic man” is an experimental failure that needs to be replaced by an alternative paradigm. This brief commentary contests the paper's caricature of economic theory, and offers a small sample of the enormous volume of experimental data that would need to be overturned before “economic man” could be junked.

Henrich et al. describe an innovative research program investigating cross-cultural differences in the selfishness axiom (in economic games) in humans, yet humans are not the only species to show such variation. Chimpanzees and capuchin monkeys show signs of deviating from the standard self-interest paradigm in experimental settings by refusing to take foods that are less valuable than those earned by conspecifics, indicating that they, too, may pay attention to relative gains. However, it is less clear whether these species also show the other-regarding preferences seen in humans.

Although provocative, the data reported in Henrich et al.'s target article suffer from limitations, including the fact that the “selfishness axiom” is not an interesting null hypothesis, and the intrinsic limitations of quasi-experimental designs, in which random assignment is impossible. True experiments, in the laboratory or in the field, will continue to be crucial for settling core issues associated with human economic behavior.

Replacements for the self-interest axiom may posit weak to strong theories of sociality. Strong sociality may be useful for positing social cognitive mechanisms and their evolution, but weak sociality may work better for identifying interesting group-level outcomes by focusing on deviations from self-interested psychological assumptions. Such theoretical differences are likely to be based on disciplinary expertise, and the challenge for Darwinian integration is to keep the conversation flowing.

The data of Henrich et al., when combined with other research, suggest that sharing behavior probably varies systematically across cultures, situations, and individuals. Economic policies founded on recognition of this “radical contingency” would, I argue, nurture economic pluralism rather than attempting to bring the world under one system.

Future economic game research should include: (1) within-culture comparisons between individuals exposed and not exposed to market integration; (2) use of a game (such as the “Sharing Game”) that enables subjects to maximize their earnings while also maximizing those of the other participant; and (3) assessment of performance in a repeated-trials format that might encourage sensitivity to the games' economic contingencies.

We argue that the lack of large cross-cultural differences in many games with student subjects from developed countries may be due to the nature of the games studied. These games tap primarily basic psychological reactions, like fairness and reciprocity. Once we look at norm-enforcement, in particular punishment, we find large differences even among culturally rather homogeneous student groups from developed countries.

The Ultimatum Game is commonly interpreted as a two-person bargaining game. The third person who donates and may withdraw the money is not included in the theoretical equations, but treated like a neutral measurement instrument. Yet in a cross-cultural analysis it seems necessary to consider the possibility that the thoughts of a player – strategic, altruistic, selfish, or concerned about reputation – are influenced by both an anonymous second player and the non-anonymous experimenter.

The predictive validity of the ultimatum game (UG) for cross-cultural differences in real-world behavior has not yet been established. We discuss results of a recent meta-analysis (Oosterbeek et al 2004), which examined UG behavior across large-scale societies and found that the mean percent offers rejected was positively correlated with social expenditure.

I argue that altruistic behavior and its variation across cultures may be caused by mental cognitive mechanisms that induce cooperative behavior in contract-like situations and adapt that behavior to the kinds of contracts that exist in one's socio-cultural environment. I thus present a cognitive alternative to Henrich et al.'s motivation-based account. Rather than behaving in ways that reveal preferences, subjects interpret the experiment in ways that cue their social heuristics. In order to distinguish the respective roles of preferences and cognitive processes that determine economic behavior, we need more ethnography of strategies “in the wild.”

The target article authors' study has highlighted the relationship between market integration and an increased willingness to enter into cooperative exchanges. Less developed, albeit implied, in their analysis are the theoretical implications of their findings for the theory of altruism first developed by Adam Smith and later expanded in the works of the American historian, Thomas Haskell.

Diverse cultural norms governing economic behavior might emerge from a dynamic interaction of universal but flexible predispositions that get calibrated to biologically meaningful features of the local social and physical ecology. This impressive cross-cultural effort could better elucidate such gene-culture interactions by incorporating theory-driven experimental manipulations (e.g., comparing kin and non-kin exchanges), as well as analyses of mediating cognitive processes.

Henrich et al.'s nice cross-cultural experiments would benefit from models that specify the decision rules that humans use and the specific developmental pathways that allow cooperative norms to be internalized. Such models could help researchers to design further experiments to examine human social adaptations. We must also test whether the “same” experiments measure similar constructs in each culture, using additional methods and measures.

Henrich et al. propose that humans are genetically equipped with learning mechanisms that enable them to acquire the preferences and beliefs related to economic prosocial behaviors. In addition to their cross-cultural data, they cite developmental evidence in support of this theory. We challenge Henrich et al.'s interpretation of the developmental data in a discussion of recent work which suggests that preferences for altruism and fairness may have an innate basis.

We discuss the implications of the findings reported in the target article for moral theory, and argue that they represent a clear and genuine case of fundamental moral disagreement. As such, the findings support a moderate form of moral anti-realism – the position that, for some moral issues, there is no fact of the matter about what is right and wrong.

Tests of economic theory often focus on choice outcomes and find significant individual differences in these outcomes. This variability may mask universal psychological processes that lead to different choices because of differences across cultures in the information people have available when making decisions. On this view, decision making research within and across cultures must focus on the processes underlying choice.

The target article summarizes important research demonstrating that the canonical model of selfish, economic man is not empirically supported outside competitive settings, and that experimental research conducted in university settings should not be discounted because undergraduates were the subjects. Assuming that individuals are capable of reciprocity and trust provides a firmer foundation for the study of institutions, incentives, and outcomes.