Static and Kinetic Conditioned Reactions. ∗

Abstract

Former experiments of Spiegel 1 , 2 and his coworkers (Aronson, 3 Price 4 and Spiegel) indicated that labyrinthine impulses may reach the cerebral cortex.

In order to investigate what part the connections of the labyrinth with higher centers play in the perception of position and motion, the study of conditioned reactions seemed promising. A special position table was built allowing dogs to be brought into any desired position. The dogs were slowly rotated from a sloping position through the horizontal plane into another oblique position. When the horizontal plane was passed, an electric shock (unconditioned stimulus) was applied to a leg, during the motion in one direction only; the defense reaction and the change in respiration were recorded. First, only conditioned reactions upon the horizontal position appeared. Later the animals learned also to differentiate between the direction of the motion accompanied by the unconditioned stimulus in the horizontal position (up or downwards) and the motion in the opposite direction during which the unconditioned stimulus was omitted. Thus static as well as kinetic conditioned reactions could be developed. These reactions appeared in the majority of our observations before the horizontal position was reached; in other words, they were mainly anticipatory in nature. In these cases the first appearance of conditioned reactions could be observed without omitting the unconditioned stimulus. Conditioned reactions in exactly the horizontal position were, however, also observed. The inference that we have here to do with conditioned reactions is based upon the fact that these reactions did not exist before the animals were trained, and that they showed typical characteristics of conditioned reactions, such as inhibition by fortuitous external stimuli, or extinction after repeated application of the conditioned stimulus without reinforcement by the unconditioned one. The strength of these conditioned reactions may sometimes exceed that of the unconditioned defense reflexes.

The effect of various peripheral and central lesions (elimination of labyrinthine and other afferent impulses, destruction of cortical areas) upon these conditioned reactions will be reported later.