ANALYSIS OF ACTIVITY OF RAT

The Cause of Activity

Methods.

Rats habit about when they are getting food or water nest material; when they are finding a mate or site for nesting; and when they are fleeing from predator. But their movements are often by no means obviously related to such activities. To what extent are rats’ movements determined by immediate need?

Laboratory rats have long been described as highly exploratory and inquisitive. One of the earliest studies, that of Small, published in 1899, describes this behavior at length and refers to the restlessness of infant rats as ‘premonitions of curiosity’.

Wild rats, too, are actively exploratory, though this is often obscured by a form of ‘wariness’ which laboratory rats hardly display. Generalized movement about a substantial area can, however, easily be observed in wild rats given access to a strange place; this can be arranged by removing a barrier which has hitherto prevented entry by rats living on adjacent ground, or by putting rats in large and unfamiliar cage.

Sometimes it is possible to account for the movements of an animal in common sense term. In natural condition, and in captivity also, activity may seem obviously to spring from some internal deficit; after an interval without food or water, an animal which has been sleeping or resting goes to a place where it can eat or drink. But not all the ranging movements of rats can be explained in this way.

Consider, for instance, rats which have been deprived of food for twenty-four hours. While they have eaten a good deal and have drunk some water, they carry out a general exploration of the cage. Evidently, in this situation, exploration comes after deficit has been made up.