Localization of Prey
In this chapter we present an action-oriented model of the spatial localization of prey by frogs and toads. Instead of building a global depth map, we propose that the goal of catching prey can lead a frog or toad to select a particular region of its visual world for special scrutiny. We suggest that the first step of the prey-catching sequence is not an overt movement, but a covert movement to adjust the accommodative state of the lenses and thus lock the visual apparatus on to a stimulus. We demonstrate how prey localization can be acheived rapidly and accurately by coupling prey-selection and lens-accommodation processes within a feedback loop. Information derived from prey selection supplies a setpoint for accommodation. In turn, adjustment of the lens modifies the visual input and can alter the prey selection process. The natural feedback of this goal-seeking system automatically corrects for the problem of ambiguity in binocular matching. We tie the model to the known anatomy, physiology, and behavior of frogs and toads, identifying brain regions that could provide the neural substrates necessary to support the model’s various functional stages. We also present experiments, with a computer simulation, that compare the model’s functioning with animal behavior.
KeywordsDepth Estimate Pattern Recognizer Retinal Position Inhibitory Layer Angular Disparity
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