Generalization Gradients and Combined-Stimulus Control after Equal Training with Two Related Stimuli 1

Abstract

A technique was developed to study stimulus control of behavior by a combination of training stimuli and by a stimulus intermediate to the training stimuli. 2 pigeons’ keypecking responses were maintained by variable-interval schedules of grain presentation when either of two vertically aligned lamps (Lamp 3 or Lamp 5) was lit. Responses when neither lamp was lit ceased when this condition was correlated with the absence of grain (extinction). Test presentations in extinction of a series of vertically aligned lamps (Lamps 1 to 7) showed orderly generalization gradients for both birds, with the peak of responding occurring at either one of the training stimuli or the intermediate stimulus. Furthermore, as part of the same extinction test, the combined training stimuli (Lamps 3 plus 5) controlled a greater number of responses than any single stimulus.