Conditioning of Fear: A Function of the Delay of Reinforcement

Abstract

The purpose of this study was to investigate the effect of delayed reinforcement on the acquisition of a conditioned emotional response. Specifically, the experiment was designed to determine the effect of paired presentation of a blinking light and an electric shock with various intervals of delay between the conditioned stimulus (CS) and the unconditioned stimulus (US). The empirical fact that the strength of association is a function of the temporal proximity of the elements to be associated has long been recognized as a fundamental principle of learning. Critical reviews of the experimental evidence related to this phenomenon have been made by Spence and by Hilgard and Marquis.1 In 1947, Spence summarized some of the existing research on the delay of reinforcement for instrumental learning. His review indicated that consistently shorter gradients of reinforcement had been obtained when the operation of secondary reinforcement had been minimized. He concluded as follows: