In two studies, we investigated the influence of aversive and nonavers
ive reinforcers on startle reactivity, visceral responses, and self-re
port during Pavlovian conditioning. Furthermore, we assessed how aware
ness of the stimulus contingencies affect conditioned discrimination i
n the different response systems. Conditioned potentiation of the star
tle response was only observed in the context of aversive learning. Mo
reover, blink potentiation occurred without awareness of the relations
hip between the conditioned and unconditioned stimulus. In contrast, s
kin conductance conditioning was independent of the aversiveness of th
e reinforcer and was only obtained for those individuals who could cor
rectly verbalize the stimulus contingency in a postconditioning recogn
ition test. Cardiac responses varied with the task demands of the situ
ation and covaried with individual response stereotypes.