1. a phenomenon, observed in stimulus generalization, which takes place after discrimination training comprising two stimulants across a typical dimension. The peak of the response gradient is moved slightly in a direction veering away from the lesser desired stimulant to a place past the value of the stimulant correlated with reinforcement. 2. with regard to aesthetics, the phenomenon postulating that an extreme type of a favored stimulant is desired more than the normal type of said stimulant.