Modification of a visceral response, salivation in thirsty dogs, by instrumental training with water reward.

Thirsty dogs rewarded by water for bursts of spontaneous salivation showed progressive increases in salivation, while other dogs, rewarded for brief periods without salivation, showed progressive decreases. No obvious motor responses were involved, but dogs rewarded for decreasing salivation appeared more drowsy than those rewarded for increasing it. Implications for learning theory and psychosomatic medicine are mentioned.