INFORMATION-PROCESSING AND PREY DETECTION

We present a model to examine how foragers should divide attention among different potential prey types in order to maximize their net rate of energy intake. We define attention as the brain's capacity to process information simultaneously. Our model is based on neuropsychological studies suggesting first, that predators who divide attention among an increasing number of different prey types decrease their ability to detect any given type, and second, that this decrease is larger when prey items are more difficult to detect. Our model also incorporates the effects of search rate on foragers' probability to detect prey. The model predicts that foragers encountering cryptic prey should devote all attention to a single prey type. When encountering conspicuous prey, foragers should divide attention among the different prey types. For prey types that differ in conspicuousness but are equal in energy content, handling time, and density, foragers should give more attention to the more conspicuous prey if the conspicuousness values of all prey types are relatively small. However, when all prey are more conspicuous, foragers should devote more attention to the less conspicuous prey type. We suggest that our model may serve to explain and predict some of the foraging decisions of animals searching for cryptic or conspicuous prey, and especially studies on ''search image'' formation.