Play behavior in the year-old infant: early sex differences.
D005260:Female; D005639:Frustration; D006801:Humans; D007223:Infant; D008297:Male; D008425:Maternal Behavior; D009034:Mother-Child Relations; D010988:Play and Playthings; D012737:Sex Factors; D013037:Spatial Behavior; D014110:Touch; D014705:Verbal Behavior