Behavioural deception.

Theoretical models predict that deception should occur even in stable signalling systems. Assessment of the prevalence of deception and its importance has, however, been hampered by the lack of a rigorous definition of what constitutes deception and by the anecdotal nature of much of the literature. For an interaction to qualify as deception, the receiver of the "deceptive" signal must incur a cost. While this cost is often clear in interspecific interactions, it is more difficult to evaluate in interactions between members of the same species. A systematic approach to the study of deception, including the use of experimental techniques to elicit deceptive behaviour, is now required. Such an approach may enable us to address a crucial question in social evolution - whether animals are capable of manipulating the minds of others, or merely their behaviour.