How animals make assessments: information gathering by the hermit crab Pagurus bernhardus

Abstract

The process by which animals gather the information required to make a decision on whether or not to accept a resource was examined. A motivational model was developed to predict how information changes levels of causal factors and the model was tested by experiments on hermit crabs investigating shells. A prediction of the model is that, when there is a high utility in accepting the resource, each stage of the assessment procedure will be rapid, whereas if the utility is low the assessment will be prolonged. If the resource is not available for some reason, for example if a shell has the aperture blocked, the animal will persevere for longer if the initial stages of assessment indicated a high-quality resource than if it had indicated a low-quality resource. These and other predictions of the model were upheld in experiments in which the information available to hermit crabs at each stage of assessment was varied.