title: Problem length and multiple discrimination learning in retarded children.
mesh_terms: D000293:Adolescent; D001288:Attention; D002648:Child; D003216:Conditioning, Operant; D004193:Discrimination Learning; D004495:Education of Persons with Intellectual Disabilities; D005556:Form Perception; D006801:Humans; D011340:Problem Solving; D012055:Reinforcement Schedule; D012201:Reward; D013997:Time Factors