EXPLICITLY‐UNPAIRED AND TRULY‐RANDOM CS—CONTROLS IN HUMAN CLASSICAL DIFFERENTIAL AUTONOMIC CONDITIONING

Abstract

ABSTRACT The conventionally used explicitly‐unpaired CS– (euCS–) of the differential conditioning paradigm, a stimulus which is negatively correlated with the US, may generate inhibition and hence be an inappropriate control for CS+ conditioning. An implication of this possibility is that the CS+:euCS– performance difference should exceed the difference between CS+ performance and performance to a truly‐random CS– (trCS–), a stimulus which is uncorrelated with US occurrence. This implication was tested in a 5‐sec delay conditioning skin resistance response study (Exp. I, N = 32) and an 8‐sec delay conditioning plethysmographic digital pulse volume response study (Exp. II, N = 48). While highly reliable discrimination between CS+ and the two control CSs (euCS– and trCS–) was obtained in both experiments, neither experiment yielded the outcome expected from the position that euCS– generates inhibition.