| In the present research, the degree of stimulus control exerted by each of the two dimensions (color and shape) of compound stimuli was studied in two experiments with undergraduate college students. A between-groups design with three consecutive experimental phases was used in each experiment. Phases 1 and 2 were training phases; Phase 1 consisted of single stimulus discrimination training and Phase 2 consisted of compound stimulus discrimination training. Phase 3 was testing in which stimuli were presented to assess the degree to which responding corresponded to the Phase 2 training. In Experiment 1, congruence of reinforcement contingencies between training phases was manipulated for a target dimension in a graded manner---100%, 25%, or 0%. There was a systematic decrease in the level of Phase-2-consistent responding in the presence of the target dimension corresponding to the decreases in the level of congruence present during Phase 2. In Experiment 2, training history for the non-target dimension was altered in order to influence the extent to which the non-target dimension exerts stimulus control. The three experimental conditions under which the Phase 1 training history for the non-target dimension was manipulated were: (a) Correlated with reinforcement, as in Experiment 1, (b) Absent, or (c) Not Correlated consistently with reinforcement. Under the Absent condition, the non-target dimension was not presented in Phase 1. Under the Not Correlated condition, inconsistent prior training for the non-target dimension was presented. The identical manipulation of the congruence of the reinforcement contingencies for the target dimension used in Experiment 1 was used in Experiment 2. There was an effect of the manipulation of the prior training history for the non-target dimension on the level of Phase-2-consistent responding in the presence of the target dimension. Correlated prior training compared to Absent and Not Correlated prior training for the non-target dimension led to greater competition, indicated by high Phase-2-consistent responding in the presence of the non-target dimension and reduced target performance. |
