Pavlovian orienting reflex.

The concept of the orienting reflex is discussed from the historical perspective. The following conclusions are proposed: (1) in accordance with the spirit of Pavlov's concept the orienting reflex is a response to a stimulus unexpected in a given situation; (2) the reflex consists of targeting, arousal and perceptual components; (3) the reflex has three stages, which in the targeting component are represented by the movement towards the stimulus, the maintenance of fixation of the stimulus and the return movement; (4) when the reflex is evoked by a new stimulus, perceptual learning occurs in its second stage. The non-orienting targeting reflexes are reviewed. The pretrigeminal cat is discussed as a model for investigation of the ocular orienting reflex.