Effects of aversive classical conditioning on habituation of unconditioned skin conductance response

The purpose of this experiment was to investigate the effect of classical conditioning on the amplitude of the unconditoned response (UR). The conditioned stimulus (CS) was a 340 Hz tone, and the unconditioned stimulus (US) consisted of a white noise with an intensity of 105 dBs. Twenty five subjects were presented with 20 trials of delayed conditioning, with an interval between the CS and the US of 0.5 seconds (s). A further 25 subjects received the same number of presentations of both stimuli, but in an explicitly randomized order. The dependent variable was the amplitude of the skin conductance response (SCR) elicited by the US on each trial, The results showed that the amplitude of the SCR decreased throughout the acquisition trials in both groups. However, a greater decrease in SCR was observed in the conditioning group. It can be concluded, therefore, that aversive classical conditioning facilitates the habituation of the unconditioned SCR.