title: Equivalence formation by mentally retarded and nonretarded children using pictorial and printed word stimulus items.
mesh_terms: D002648:Child; D002657:Child Development; D003071:Cognition; D003210:Concept Formation; D004193:Discrimination Learning; D004495:Education of Persons with Intellectual Disabilities; D006801:Humans; D007257:Information Theory; D008607:Intellectual Disability; D007360:Intelligence; D007804:Language Development; D009042:Motivation; D011340:Problem Solving; D014705:Verbal Behavior; D014796:Visual Perception