There's often "other things going on" - but here is a description of the hypothesis:

Pursuit-deterrent signals represent a form of interspecific communication, whereby the prey indicates to a predator that pursuit would be unprofitable because the signaler is prepared to escape (Woodland et al. 1980). Pursuit-deterrent signals provide a benefit to both the signaler and receiver; they prevent the sender from wasting time and energy fleeing, and they prevent the receiver from investing in a costly pursuit that is unlikely to result in capture. Such signals can advertise prey's ability to escape, and reflect phenotypic condition (quality advertisement, sensu Zahavi 1977; also see Hasson 1991), or can advertise that the prey has detected the predator (perception advertisement, sensu Woodland et al. 1980). Pursuit-deterrent signals have been reported for a wide variety of taxa, including fish (Godin and Davis 1995), lizards (Cooper et al. 2004), ungulates (Caro 1995), rabbits (Holley 1993), primates (Zuberbühler et al. 1997), rodents (Shelley and Blumstein 2005), and birds (Alvarez 1993).

• http://beheco.oxfordjournals.org/cgi/content/full/17/4/547

Another example of signalling from prey to predator is the striped pattern on wasps.