How often do animals lie about their intentions? An experimental test.

During conflicts, animals may perform displays that convey information about their future antagonistic behavior. Although theory once predicted that such signals of "intent" would be utterly susceptible to dishonesty, empirical studies have established that animals sometimes do signal their intentions. It remains unclear, however, what level of honesty exists within such signals. Here I report interactive-model experiments designed to expose instances of falsified intent and to reveal how frequently signalers within an invertebrate population lie about their impending hostile actions. Hermit crabs (Pagurus bernhardus) were given the opportunity to aggressively threaten an approaching model, and their subsequent behavior was then examined after the model fled from them or probed them to the point of imminent collision. Discrepancies between an individual's advertised intention and what it actually did next were infrequent. If the model fled, nearly all crabs remained in place, regardless of whether they had initially threatened. If the model probed, crabs that threatened reliably stood their ground, thus backing up their threat, whereas those that did not threaten tended to back down and retreat. Much of what has been regarded as "lying about intent" in prior nonexperimental studies may actually represent uncontrolled noise, especially recipient-response dynamics.