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Babies embrace punishment earlier than previously thought

"We find that, by eight months, babies have developed nuanced views of reciprocity and can conduct these complex social evaluations much earlier than previously thought," says lead author Prof. Kiley Hamlin, UBC Dept of Psychology.

"This study helps to answer questions that have puzzled evolutionary psychologists for decades," says Hamlin. "Namely, how have we survived as intensely social creatures if our sociability makes us vulnerable to being cheated and exploited? These findings suggest that, from as early as eight months, we are watching for people who might put us in danger and prefer to see antisocial behavior regulated."

For the study, researchers presented six scenarios to 100 babies using animal hand puppets. After watching puppets act negatively or positively towards other characters, the babies were shown puppets either giving or taking toys from these "good" or "bad" puppets. When prompted to choose their favorite characters, babies preferred puppets that punished the bad characters from the original scene compared to those that treated them nicely.

The researchers also examined how older infants would themselves treat good and bad puppets. They tested 64 babies aged 21 months, who were asked to give a treat to, or take a treat away from one of two puppets – one who had previously helped another puppet, and another who had harmed the other puppet. These older babies physically took treats away from the "bad" puppets, and gave treats to the "good" ones.