Smiling in children as a function of their sense of mastery.
D000339:Affect; D002648:Child; D002652:Child Behavior; D002657:Child Development; D002675:Child, Preschool; D005149:Facial Expression; D005260:Female; D006801:Humans; D007361:Intelligence Tests; D007845:Laughter; D008297:Male; D009042:Motivation; D011336:Probability; D011340:Problem Solving; D012578:Schools, Nursery; D014796:Visual Perception