First it was "Toddlers in Tiaras," now there is Baby Judge Judy. According to a new study published in the Proceedings of the National Academy of Sciences, babies show an innate sense of justice at around eight months old. They prefer people who act nicely to those who behave badly. Moreover, babies approve of those who reprimand a third party's antisocial behavior. By about two years old, toddlers will mete out punishment themselves.
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The study's authors, led by Kiley Hamlin, a professor of psychology at the University of British Columbia, wanted to expand on research they had done on how babies prefer prosocial, or nice, behavior. "Adults see behavior in context," Kiley told Yahoo! Shine. Adults consider an act that is usually perceived as antisocial, such as restraining another person, to be a good thing under the right circumstances. The researchers wanted to see if babies could understand antisocial and prosocial behavior in similarly nuanced way. "We weren't confident they would be capable of this kind of reasoning," says Kiley. The babies proved the scientists wrong.
The researchers showed eight-month-old babies a series of simple puppet shows. During the first two, a puppet trying to open a box was either helped by a nice puppet or hindered by a mean puppet. Overwhelmingly, the babies showed a preference for the nice puppet by immediately choosing it when offered both. Less expected was their reaction to the third show. When a puppet called the Taker grabbed a ball away from the mean puppet, the babies liked the Taker.
The toddler group went a step further. They gave treats to the nice puppets as well as to the Taker. And they took treats away from the mean puppets as punishment for their bad behavior.
Kiley explains that our inclination toward rewarding positive behavior and punishing transgression has evolutionary advantages for human beings. "In order to be as intensely social and cooperative as we are, humans have to have systems to find out who is a bad guy and who is a good guy. We want to ally ourselves with good guys and also seek ways to prevent bad guys from being antisocial in the future." The team's research suggests this quest for justice is not learned but hard-wired.
The puppet study also tested five month olds. While infants clearly preferred nice puppets, they didn't favor the puppets who punished others for previous bad behavior. "We will have to do additional trials," says Kiley, "The five month olds may have just forgotten."