The prey localisation model: a stability analysis.

This paper analyzes the "Prey localisation Model" (House 1984), for animals that are unable to verge their eyes. The Prey localisation Model selects a single point or a portion of the scene in its visual space. In particular it imitates the behaviour of frogs and toads of selecting the closer target when two equally attractive prey are presented to it. The model achieves its goal by tightly coupling two prey selection processes, one for each eye, with lens accommodation. In this paper we offer a stability analysis of the model, and show how lens accommodation, i.e. adjustment in the focal length of the lens, biases the selection of the proximal target. We examine the properties of the model that are responsible for its behaviour and derive a set of conditions which guarantees the localisation of the correct target.