Food-reinforced inhibition of conditioned salivation in dogs.

Twelve dogs salivated to a tone that was followed by food, but not to a noise for which there was an added response dependency. The noise was followed by food if and only if they did not salivate. The addition of this response dependency vitiated the classically conditioned response to the noise. A yoked-control group of 6 dogs receiving the same sequences of stimuli and food salivated to both the tone and noise stimuli.