From CBC News:
“Infants prefer an individual who helps another to one who hinders another, prefer a helping individual to a neutral individual, and prefer a neutral individual to a hindering individual,” the Yale University psychology researchers report in the edition of Nature to be published Thursday.
“The findings reported here constitute the first evidence that young infants’ social preferences are influenced by others’ behaviour towards unrelated third parties,” they say. The findings show humans make social evaluations at a much younger age than previously thought.
Kiley Hamlin and colleagues tested groups of babies, either six or 10 months old, to see how they evaluated individuals based on how the individuals acted toward others.