Abstracts

Cognitive Bias and the Evolution of Self Deception

James Marshall University of Sheffield

The apparent prevalence of seemingly irrational biases in decision making by humans and other animals has recently attracted great interest. Since animal behaviour is shaped by natural selection we expect such behaviour to be optimal, and Bayesian optimality is usually taken as the appropriate criterion to apply. Despite this, recent theoretical proposals have suggested simple explanations for cognitive biases, that do not rigorously justify departures from Bayesian optimality. I will present detailed examinations of such proposals, drawing a crucial distinction between cognitive and behavioural biases. Having concluded that existing proposals are unsatisfactory, I will present the first formal model of the evolution of cognitive bias, in the form of self deception, via a mechanism informally proposed by Robert Trivers that assumes a physiological cost for separating internal decision biases from external dishonest signalling.