The psychology and social dynamics of fetal sex prognostication in China: Evidence from historical data.

Fetal sex prognostication has been a common practice in many human societies, yet most of the prognosticative methods do not perform better than chance. Why do these ineffective prognostication practices recur across societies and persist for long periods of time? In this article, we use historical texts of four different genres in traditional China (oracle bone inscriptions, dynastic history, encyclopedia, and local gazetteers) to examine the social and cognitive factors that lead to the overestimation of the predictive accuracy of sex prognostication and place fetal sex prognostication into a more general framework to understand the persistence of ineffective cultural practices. In particular, we present a detailed historical analysis showing that individuals often entertain considerable uncertainty regarding the accuracy of sex prognostication and quantitative data demonstrating a significant bias toward selectively reporting successes in (fictionalized) historical texts. We conclude by discussing how such reporting bias combined with humans' imperfect information processing may help explain the persistence of ineffective technologies, such as divination, and magic in general. [ABSTRACT FROM AUTHOR]