title: Trends in the development of representional play in infants from one to three years--an observational study.
mesh_terms: D000367:Age Factors; D002657:Child Development; D002675:Child, Preschool; D003071:Cognition; D005260:Female; D006801:Humans; D007223:Infant; D007804:Language Development; D008297:Male; D009769:Object Attachment; D010988:Play and Playthings; D012649:Self Concept; D012737:Sex Factors; D012923:Social Class; D012938:Social Perception