Direction of changes in the cardiac component in a Pavlovian conditioning paradigm with variations in CS- and...

The research reported was aimed at examining the direction of heart rate post-stimulus changes in a conditioning paradigm with fear-relevant (snakes and spiders), and fear-irrelevant (circles and triangles) slide-CSs. Furthermore, half of the subjects in each group had electric shocks as the UCS, whereas the other two halves were merely threatened about the shock. Finally, all subjects were informed at the start of the extinction about the removal of the UCS. Thus, a 2 X 2 factorial design was used. The conditioning situation involved a differential paradigm with an interstimulus interval of 8 sec. There were 12 presentations of each cue during acquisition, and 20 during extinction. The results showed reliable effects of decelerative acquisition in the fear-relevant shock group, and the fear-irrelevant threat group. During extinction, only the fear-relevant shock group showed evidence of continuing differential responding, with larger deceleration to the CS+. It is speculated that responses to fear-relevant CSs, together with shock-UCSs, share important similarities with the irrational aspect of phobic behavior, since the instructions about the omission of the UCS during extinction did not eliminate the responses to the CS+ in the fear-relevant shock group.