Martin Orne's notion of demand characteristics is related to the cooperative principle in language pragmatics: The need for experimenter and subject to have a common view of the experiment is similar to the need for speaker and listener to establish common ground in a conversation. Where experimenter and subject do not share common ground, experiments may be lacking in ecological validity. Like experimental subjects, clinical patients are engaged in effort after meaning, trying to make sense of their symptoms. In order to make sure that patient and therapist are on common ground, Orne urged clinicians to engage in anticipatory socialization and to mobilize demand characteristics in the service of treatment and prevention.