When we make moral judgments, we do so subtly and selectively. We recognise that explicitly antisocial acts can seem appropriate in the right circumstances. We know that the enemy of our enemy can be our friend. Now, Kiley Hamlin from the University of British Columbia has shown that this capacity for finer social appraisals dates back to infancy – we develop it somewhere between our fifth and eighth months of life.
Hamlin, formerly at Yale University, has a long pedigree in this line of research. Together with Karen Wynn and Paul Bloom, she showed that infants prefer a person who helps others over someone who hinders, even from the tender age of three months. These experiments also showed that infants expect others to behave in the same way – approaching those who help them and avoiding those who harm them. Now, Hamlin has shown that our infant brains can cope with much more nuance than that.
She worked with 64 babies, and showed them a video of a duck hand puppet as it tried to get at a rattle inside a box. This protagonist was aided by a helpful elephant puppet that lifted the lid (first video), but hindered by an antisocial elephant that jumped on the lid and slammed it shut (second video). Next, the babies saw the two elephants playing with a ball and dropping it. Two moose puppets entered the fray – one (the ‘Giver’) would return the ball to the elephant (third video), and the other (the ‘Taker’) would steal it away (fourth video). The babies were then given a choice between the two moose.
Hamlin found that over three-quarters of the five-month-old babies preferred the Giver moose, no matter whether it returned the ball to the helpful elephant or the antisocial one. They were following a simple rule: “helpful moose = good moose”. But the eight-month-old babies were savvier. They largely preferred the Giver moose when it was aiding the helpful elephant, but they chose the Taker when it was took the antisocial elephant’s ball.