FourCebus albifrons monkeys received 24 sessions of multiple avoidance-punishment conditioning of the skin conductance response (SCR) with no discriminative stimuli, followed by 24 additional sessions with visual discriminative stimuli identifying the avoidance and punishment components. Four other monkeys that had previously been conditioned with the discriminative stimuli were given 24 additional sessions without them. Yoked controls were run with this group and received the electric shock noncontingently. The presence of the discriminative stimuli clearly facilitated acquisition and maintenance of higher SCR frequencies in avoidance as compared with punishment. Acquisition was retarded with the stimuli absent, and higher overall response levels resulted. Adding the stimuli improved differentiation and resulted in lower overall rates. Removing the stimuli likewise resulted in higher response frequency. When the stimuli were absent initially, higher shock frequencies were administered, and when they were removed, shock frequency increased. The yoked controls increased in response frequency but did not differentiate between the avoidance and punishment conditions. Overall, the presence of the stimuli appeared to facilitate differentiation and reduce trauma, as compared with when they were absent.