Stimulus control acquired by components of two color-form compound stimuli.

Four pigeons were trained to respond on one of two keys in the presence of one color-form display, and on the other key when a second color-form display was present. Both responses were maintained on a 2-min variable-internal schedule of reinforcement. Subsequently, stimulus control acquired by components of the compound stimuli was determined by brief test probes in which the colors and forms separately, and in novel combinations, appeared on the display screen. When either color component was present, both choice of response key and response rate were like responding to the training compound display containing that color. When the forms were presented separate from the colors, generally low and comparable rates of responding occurred on both keys.