REVERSIBILITY OF SINGLE-INCENTIVE SELECTIVE ASSOCIATIONS

Rats were trained to press a lever in the presence of a tone-light com pound stimulus and not to press in its absence. In each of two experim ents, schedules were designed to make the compound a conditioned punis her for one group and a conditioned reinforcer for the other. In Exper iment 1, one group's responding produced food in the presence of the c ompound but not in its absence. The other group's responding terminate d the compound stimulus, and food was presented only in its absence. W hen tone and light were later presented separately, light controlled m ore responding than did tone in the former group, but tone gained subs tantial control in the latter. The same effects were also observed wit hin subjects when the training schedules were switched over groups. In Experiment 2, two groups avoided shock in the presence of the compoun d stimulus. In the absence of the compound, one group was not shocked, and the other received both response-independent and response-produce d shock. When tone and light were presented separately, the former gro up's responding was mainly controlled by tone, but the latter group's responding was almost exclusively controlled by light. These effects w ere also observed within subjects when the training schedules were swi tched over groups. Thus, these single-incentive selective association effects (appetitive in Experiment 1 and aversive in Experiment 2) were completely reversible. The schedules in which the compound should hav e been a conditioned reinforcer consistently produced visual control, and auditory control increased when the compound should have become a conditioned punisher. Currently accepted accounts of selective associa tions based on affinities between shock and auditory stimuli and betwe en food and visual stimuli (i.e., stimulus-reinforcer interactions) do not adequately address these results. The contingencies of reinforcem ent most recently associated with the compound and with its absence, r ather than the nature of the reinforcer, determined whether auditory o r visual stimulus control developed.