title: Operant pain: a new name for an old problem.
mesh_terms: D000203:Activities of Daily Living; D000328:Adult; D000368:Aged; D001521:Behavior Therapy; D002908:Chronic Disease; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010146:Pain / Q000209:etiology / Q000523:psychology; D059408:Pain Management; D010817:Physician-Patient Relations