Preferring for pleasure.

Recent review articles have confirmed that pleasure is a potent drive inducing forms of behavior adapted to physiological needs, especially in the case of temperature regulation and food-and-water intake. This point is accepted in the present article. The hypothesis of the usefulness of pleasure is pushed one step further by examining the results of experiments on conflicting motivations. In a conflict of fatigue vs thermal discomfort human subjects in a first series of sessions rated their fatigue and their thermal discomfort while walking on a treadmill placed in a climatic chamber. In further series of sessions the subjects could select either the treadmill slope or the ambient temperature. During these sessions the subjects behaved in such a way as to maximize the two-dimensional pleasure (or minimize the two-dimensional displeasure). Rats placed in a conflict of motivations of palatability vs cold discomfort behaved in a way that can also be interpreted as a tendency to maximize pleasure. It is therefore suggested that sensory pleasure is an incentive to useful behavior, and maximization of pleasure the answer to physiological conflicts.