[Effect of preliminary presentation of a future conditioned stimulus on the rate of elaboration of an instrumental defensive reflex in the rat].

Preliminary presentation of future conditioned stimulus without reinforcement delayed and then accelerated subsequent elaboration of defensive conditioned reflex to this stimulus in rats. Preliminary presentation of resembling stimuli influenced the speed of conditioning in a lesser degree. It is suggested that such changes are due to formation of a local conditioned reflex to the future conditioned stimulus.