Computer simulation of protective coloration with human 'predators'

Protective coloration has traditionally been studied from the perspectives of crypsis and mimicry. I suggest that these two broad categories of resemblance are more similar than has traditionally been supposed, and that predators use the same psychological decisions to identify prey whether 'cryptic' or 'mimetic'. A potential model for these psychological decisions is proposed, based on the principles of visual attention and signal detection theory, and the implications of this psychological model on the current understanding of protective coloration are discussed.Computer simulations using human subjects as 'predators' have the potential to act as model systems for the study of protective coloration, from the perspectives of both psychology and evolutionary ecology. I have developed simulations that present human subjects with both 'cryptic' and 'mimetic' stimuli in similar conditions, and use these to test hypotheses about the evolution of such protective coloration systems and the underlying psychological decisions being made by the subjects. An evaluation of the validity of the initial hypothesis is also made.Experiments show that human subjects do change their foraging strategy in response to changes in environmental conditions in ways analogous to those of more 'real' predators. Prey in polymorphic populations are predated at a slower rate than those in monomorphic populations, and this appears to be due to some kind of increased perceptual load on the predator when prey are polymorphic. Some aspects of classical mimicry theory are supported by computer simulation using human subjects, but others appear not to apply in all circumstances. The psychological basis of human foraging on simulated mimetic prey is discussed. Human subjects increase their giving up time in patches when travel time is increased in similar ways to 'real' predators.These experiments failed to prove the proposed model of predator psychology, but did indirectly confirm some of its predictions. Future work should concentrate specifically on testing the proposed model.