Abstract Thirty-two subjects, exposed to a tone CS, shock UCS simple delayed conditioning paradigm with an interstimulus interval of 8 sec, were compared in skin conductance and finger pulse volume responses to a sensitization control group of 32 subjects given unpaired CS—UCS presentations. Magnitude, probability and amplitude of anticipatory and UCS omission responses were measured. Significant conditioning effects for both these types of response were observed using magnitude and probability measures of the two effector systems. Between-subject correlations showed significant positive relationships between vasomotor and electrodermal CS responses in the sensitization group and early in conditioning training. Later in training, however, this relationship disappeared, indicating a learned dissociation of the response systems during classical conditioning. Within-subject correlations showed that the two response systems developed quite independently over trials.