Blocking as a function of added cue intensity

Twelve rats were initially trained to leverpress for water in the presence of a tone. Responses in the absence of the tone were never reinforced. Following this pretraining, a novel light cue was simultaneously compounded with all presentations of the tone as a relevant but redundant predictor of reinforcement. For three different groups of subjects, the light cue was of either bright, moderate, or dim intensity. After compound training, all subjects experienced nonreinforced presentations of each of the two components of the compound. Results indicated that the relative degree of control exerted by the light over behavior increased with increases in light (added cue) intensity.