Infants follow the gazes of robots who adults treat as people, a study shows, but ignore ones they don't. The study offers clues to how children learn to think of others as people, not things.

"Children learn from us all the time, even when we think they aren't watching," says psychologist Andrew Meltzoff of the University of Washington in Seattle. "One of the things they are watching is who we treat as thinking beings."

In the Neural Networks journal, Meltzoff and colleagues, tested "gaze following", the basic ability to direct your attention to where you see others looking. "Although adults follow a person who re-orients his head towards an object in external space, they do not do so when a swivel chair spins or a teapot rotates about its vertical axis. What defines a perceiver worth following, and how does an infant recognize one?," asked the study.

So, the team tested 64 infants, aged 18 months, in a lab equipped with toys and a robot hidden behind a screen. After letting the infants play, they removed the screen and let the kids see the robot. In some tests, an adult talked to the robot and played a game with it. In others, the adult ignored the robot.

After the adult left the room, the robot beeped and then turned its head to look at a toy to the side of the infant. In cases where the adult had played with the robot, the infant was four times more likely to follow the robot's gaze to the toy. "It is a highly significant statistical result," Meltzoff says.

The result has several implications. One is that companion robots or tutors for kids should be treated like people, essentially, to orient the kids to perceive them as worth regarding. Another is that social robots, now being used as a low-stimulus tool to teach autistic children who have trouble with gaze following, might work better if treated as people in their introductions. Another is the insight into how children learn who is a thinking person, a key question for psychologists trying to figure out how we come to understand the people around us during childhood.

"I'm not saying people need to buy a companion robot, nothing of the sort," Meltzoffsays. "But we think it is a very interesting result."