On the Source of Human Irrationality

Reasoning and decision making are error-prone. This is often attributed to a fast, phylogenetically old System 1. It is striking, however, that perceptuo-motor decision making in humans and animals is rational. These results are consistent with perceptuo-motor strategies emerging in Bayesian brain theory that also appear in human data selection. People seem to have access, although limited, to unconscious generative models that can generalize to explain other verbal reasoning results. The error does not emerge predominantly from System 1, but rather seems to emerge from the later evolved System 2 that involves working memory and language. However, language also sows the seeds of error correct- tion by moving reasoning into the social domain. This reversal of roles suggests key areas of theoretical integration and new empirical directions.

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