Dan Sperber

The spatial composition of human portraits obeys historically changing cultural norms. We show that it is also affected by cognitive factors that cause greater spontaneous attention to what is in front rather in the back of an agent. Scenes with more space in front of a directed object are both more often produced and judged as more aesthetically pleasant. This leads to the prediction that, in profile‐oriented human portraits, compositions with more space in front of depicted agents (a “forward bias”) should be over‐represented. By analyzing a large dataset (total N of 1,831 paintings by 582 unique identified European painters from the 15th to the 20th century), we found evidence of this forward bias: Painters tended to put more free space in front of, rather than behind, the sitters. Additionally, we found evidence that this forward bias became stronger when cultural norms of spatial composition favoring centering became less stringent.

Reasoning is generally seen as a means to improve knowledge and make better decisions. However, much evidence shows that reasoning often leads to epistemic distortions and poor decisions. This suggests that the function of reasoning should be rethought. Our hypothesis is that the function of reasoning is argumentative. It is to devise and evaluate arguments intended to persuade. Reasoning so conceived is adaptive given the exceptional dependence of humans on communication and their vulnerability to misinformation. A wide range of evidence in the psychology of reasoning and decision making can be reinterpreted and better explained in the light of this hypothesis. Poor performance in standard reasoning tasks is explained by the lack of argumentative context. When the same problems are placed in a proper argumentative setting, people turn out to be skilled arguers. Skilled arguers, however, are not after the truth but after arguments supporting their views. This explains the notorious confirmation bias. This bias is apparent not only when people are actually arguing, but also when they are reasoning proactively from the perspective of having to defend their opinions. Reasoning so motivated can distort evaluations and attitudes and allow erroneous beliefs to persist. Proactively used reasoning also favors decisions that are easy to justify but not necessarily better. In all these instances traditionally described as failures or flaws, reasoning does exactly what can be expected of an argumentative device: Look for arguments that support a given conclusion, and, ceteris paribus, favor conclusions for which arguments can be found.

Henrich and Boyd (2002) were the first to propose a formal model of the role of attraction in cultural evolution. They came to the surprising conclusion that, when both attraction and selection are at work, final outcomes are determined by selection alone. This result is based on a deterministic view of cultural attraction, different from the probabilistic view introduced in Sperber (1996). We defend this probabilistic view, show how to model it, and argue that, when both attraction and selection are at work, both affect final outcomes.

Someone asked ‘What time is it?’ when her watch reads 3:08 is likely to answer ‘It is 3:10.’ We argue that a fundamental factor that explains such rounding is a psychological disposition to give an answer that, while not necessarily strictly truthful or accurate, is an optimally relevant one (in the sense of relevance theory) i.e. an answer from which hearers can derive the consequences they care about with minimal effort. A rounded answer is easier to process and may carry the same consequences as one that is accurate to the minute. Hence rounding is often a way of optimising relevance. Three simple experiments give support and greater precision to the view that relevance is more important than strict truthfulness in verbal communication.

The article revisits the old controversy concerning the relation of the mother's brother and sister's son in patrilineal societies in the light both of anthropological criticisms of the very notion of kinship and of evolutionary and epidemiological approaches to culture. It argues that the ritualized patterns of behavior that had been discussed by Radcliffe-Brown, Goody and others are to be explained in terms of the interaction of a variety of factors, some local and historical, others pertaining to general human dispositions. In particular, an evolved disposition to favor relatives can contribute to the development and stabilization of these behaviors, not by directly generating them, but by making them particularly "catchy" and resilient. In this way, it is possible to recognize both that cultural representations and practices are specific to a community at a time in its history (rather than mere tokens of a general type), and that they are, in essential respects, grounded in the common evolved psychology of human beings.