Diminution and recovery of the UCR in delayed and trace classical GSR conditioning.

Abstract

Since previous research had shown that the CS [conditioned stimulus] appears to play the crucial role in UCR [Unconditioned response] decrement, a study was done in which the effects of CS duration on this diminution phenomenon could be evaluated. Four groups of 16 Ss [subjects] recieved 16 paired or unpaired tone-shock presentations with either a short or a long CS followed by 4 UCS-only test trials. The dependent variable was the GSR [Galvanic skin response] measured within 4 sec. following stimulus onset. The results showed a significantly greater degree of UCR decrement during acquisition for the Ss in the paired groups. Also Ss in the paired groups differed significantly (in favor of the delayed CS) in amount of UCR recovery as a function of CS duration during acquisition. It was concluded that a conditioned inhibitory process under the control of the CS vac one of the factors responsible for UCR decrement in classical conditioning.