A congenital contribution to emotional response in early infancy and the preschool period.
Four follow-up studies carried out from the newborn period in three different laboratories have shown that a slow, low-magnitude reaction of the newborn to interruption of sucking is associated in later infancy and the preschool period with the expression of pleasurable emotional response. The basic test of the newborn's response varied slightly in the four studies, but essentially it consisted of establishing a baseline of infant behaviour during 30 to 120 seconds of sucking on a pacifier, then recording amount of (a) bodily activity, (b) crying, (c) the latency to either or both, in the 30- to 135-second period after removal of the nipple. The three aspects of the reaction are consistently intercorrelated, even when allowances are made for artifactual interdependence. Newborns who respond quickly to interruption of sucking also continue to cry and move a lot. Up to the first month a slow, low-magnitude reaction of the newborn is associated with a later low rate of smiling, but beyond the third month there is an inversion and the association is consistently with various manifestations of postive emotional expression.
D000367:Age Factors; D002652:Child Behavior; D002657:Child Development; D002675:Child, Preschool; D003448:Crying; D004644:Emotions; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D009043:Motor Activity; D011930:Reaction Time; D012737:Sex Factors; D012904:Smiling; D013391:Sucking Behavior; D013694:Temperament