A study of exploratory behavior as an index of spatial knowledge in hamsters

This experiment investigated the role of exploration in the formation of maps of the environment. The effects of spatial rearrangement of four familiar objects in an open field on subsequent exploratory behavior were studied in hamsters (Mesocricetus auratus). During two exploratory sessions, four groups of subjects were exposed to objects in a particular spatial relation to each other and to a distal pattern. During a testing session, the control group was exposed to the same situation as during the first two sessions, and the three experimental groups were exposed to various object rearrangements. The hamsters in the experimental groups, but not those in the control group, renewed their exploration of the objects during the testing session, as measured by the number of contacts with the objects and the time spent investigating them. Further analyses of the nature of the reinvestigated objects (i.e., displaced or nondisplaced) support the hypothesis that, through exploration, a long-lasting representation of the environment is built up on the basis of the topological relations among the objects, the overall geometric structure provided by the arrangement of the objects, and the relations between the objects and extra-apparatus landmarks.