Predator attack patterns influence vigilance in a virtual experiment

Abstract: The frequency and unpredictability of predator attacks can substantially influence vigilance patterns in prey animals. However, the lack of control over predator behavior hampers our understanding of the effect of predator attack patterns on vigilance. To circumvent this limitation, I developed a virtual experiment in which the behavior of the (virtual) predator was under full control of the experimenter. In the virtual experiment, I altered the frequency and unpredictability of attacks to document how human subjects (N = 45), which acted as surrogate prey, altered their vigilance in response to changes in predator attack patterns. Subjects increased the frequency of their vigilance bouts when the virtual predator attacked more frequently and increased vigilance bout duration when the predator attacked more unpredictably, thus showing an increase in vigilance when predation risk increased. Other features of vigilance in the virtual environment also fitted predictions from current theories of vigilance. In particular, subjects overemphasized safety in the early stages of the experiment when learning about predator attack patterns. Strong individual differences in both the frequency and duration of vigilance bouts also emerged in the virtual environment. Such individual differences feature prominently in the vigilance literature in birds and mammals. The virtual environment thus provides a unique tool to assess vigilance patterns in a controlled environment. Significance statement: Predator attacks can vary substantially in frequency and unpredictability. Patterns of predator attacks are likely to influence vigilance patterns in prey animals. However, the lack of control over predator behavior hampers our understanding of the effect of predator attack patterns on vigilance. To circumvent this limitation, I developed a virtual experiment in which the predator was under full control of the experimenter. I altered the frequency and unpredictability of attacks to document how human subjects, which acted as surrogate prey, altered their vigilance in response to changes in predator attack patterns. The results show that subjects changed the frequency and duration of vigilance bouts in response to changes in predator attack patterns. The virtual experiment provides a unique tool to assess vigilance patterns in a controlled environment.