Abstract
The aims of this study were to examine how information gained during an assessment process could alter the motivational state of an animal, and how that information was gathered. The animal used was the hermit crab Pagurus bernhardus , the assessment process observed being that carried out by the crab during shell selection. The crabs were shown to discriminate between, and demonstrate preferences for, different sizes and species of shells by gathering information concerning shell quality both visually and from physical manipulation of the shell. The physical investigation was shown to consist of a series of decision points with information gathered throughout the investigation accumulating to affect the outcome of each decision. A model is presented and tested to explain the effects of the information gathered on the animals motivational state.The changing motivational state of the animal during the assessment process was further demonstrated by the use of an interruption technique. This technique demonstrated that the motivation of a crab to continue with an investigation increases or decreases during that investigation depending on the information gained.
Hermit crabs were also demonstrated to have the ability to remember information about shells, either the positions of a number of shells or more specific information about individual shells which they had just investigated.
This remembered information could reduce the amount of time wasted by shortening or preventing further investigations. That hermit crabs can carry out a complex assessment of a particular resource, and that information gathered during that assessment can be remembered such that it not only alters the motivational state of the animal when it is gathered but can continue to do so for some time, will serve to demonstrate the importance of information gathering and memory to the study of animal behaviour in general.
| Date of Award | Dec 1988 |
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| Original language | English |
| Awarding Institution |
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| Sponsors | Science and Engineering Research Council |
| Supervisor | Robert Elwood (Supervisor) |