Although there are many criticisms of Skinner's work, many textbooks and theorists like Noam Chomsky label Skinnerian or radical behaviorism as S–R (stimulus–response, or to use Skinner's term, "respondent"),[4][5] or Pavlovian psychology, and argue that this limits the approach. Although contemporary psychology rejects many of Skinner's conclusions, his work into operant conditioning which emphasizes the importance of consequences in modifying discriminative responses is useful when combined with current understandings about the uniqueness of evolved human thought over other animals.