The influence of time of day on infant social initiative.
D002652:Child Behavior / Q000502:physiology*; D002940:Circadian Rhythm; D005221:Fatigue / Q000523:psychology; D005260:Female; D006801:Humans; D007223:Infant; D007398:Interpersonal Relations; D008297:Male; D010988:Play and Playthings; D012919:Social Behavior