Intrinsic exploration in animals: motives and measurement.

Intrinsic exploration involves exploratory acts that are not instrumental in achieving any particular goal other than performance of the acts themselves. Of the theories proposed to account for the motivation of intrinsic exploration in animals, concepts of exploratory drive, optimal arousal and fear have featured prominently. But since no single approach has adequate explanatory or predictive power, it is probably sufficient to go no further than accept that organisms may have some type of `need' for sensory change which can be satisfied mainly by intrinsic exploration. Attempts to measure the phenomenon in the laboratory can be divided into forced tests in which locomotion and other motor responses are recorded in animals placed into a totally novel environments, and free tests involving measurements of active choices of differing degrees of novelty. Because of the difficulty of distinguishing between extrinsic and intrinsic exploration with activity indices, tests of free exploration are always preferable. These include novelty-related location preferences (including spontaneous alternation and responses to brightness change), object exploration and learning for exploratory rewards all of which can be viewed as reasonably valid measures of intrinsic exploration to a greater or lesser extent.