Motivational change during resource assessment by hermit crabs

• Published in: Journal of experimental marine biology and ecology Vol. 193; no. 1; pp. 41 - 55
• Main Author: Elwood, Robert W.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 29.11.1995
• Subjects: Assessment; Decision-making; Hermit crab; Information gathering; Marine; Pagurus bernhardus; Decision-making; Hermit crab; Information gathering; Assessment
• ISSN: 0022-0981; 1879-1697
• DOI: 10.1016/0022-0981(95)00109-3

Hermit crabs offer unique opportunities in studying the underlying motivational mechanisms involved in resource assessment. In particular, when assessing shells, the information gathered must influence the motivational state and the processes of motivational change may be elucidated by experimentation in two main ways. First, by stopping the sequence of assessment, either by blocking the shell aperture with cement or by sticking the shell, aperture down, to the substrate. This enables the duration for which the crab persists in assessing the shell to be measured. Second, by presenting a novel, potentially startling, stimulus at some point in the assessment and measuring the duration of the startle response. With the first method persistence time should show a positive correlation with motivation to acquire the new shell, whereas, with the second method, the duration of the startle response should be negatively correlated with that motivational state. Because the motvational state must reflect the information the crab has at any moment, these two methods provide independent ways of probing the acquisition of information. The fact that shell assessment is easily observed and quantified in the laboratory and that the resource (shell) may be experimentally modified in numerous ways, makes these crabs the ideal subjects with which to develop a general model of resource assessment.