When that mother and infant lock eyes, and the infant's old enough to have a social smile, what happens -- spontaneously -- is the eruption of joy on the part of the mother.
Når moren og barnet kigger hinanden i øjnene, og spædbarnet er gammelt nok  til at have et socialt smil, sker der det, at - spontant - udbrydes lykke fra moderens side.