Two monkeys were trained on a three-component multiple schedule using discrete trials. In one component (food), a response terminated a red stimulus and produced food and S(Delta). In the second component (avoidance), a response terminated a green stimulus and avoided shock. In the third component (optional), a response terminated a blue stimulus and produced S(Delta). The consequence of not responding in the blue stimulus, however, was the production of either a food or an avoidance trial. Manipulation of these consequences showed that when food trials were available only a small percent of the time after optional trials, the subjects tended not to respond in the blue, even though this led to an increase in the total number of avoidance trials per day. If only avoidance trials followed as a consequence of not responding in the optional component, the animals terminated the blue stimulus and avoided the avoidance trials. Throughout the experiment both subjects maintained consistently low shock rates (about 10 per day) and these were not affected by the various manipulations. The data suggest that a stimulus associated with avoidance can be a conditioned aversive stimulus and will maintain a more remote avoidance response under certain conditions.
