A simple computer game reveals how able volunteers are to put themselves on the shoes of others. Click the link below to see the frames in full detail (Image: Iroise Dumontheil/Developmental Science) Instructions example: player’s view (Image: Iroise Dumontheil/Developmental Science) Instructions example: other person’s view (Image: Iroise Dumontheil/Developmental Science) Experimental trial: volunteers have to move the small ball the other person can see (Image: Iroise Dumontheil/Developmental Science) Advertisement Control trial: other person can see all balls (Image: Iroise Dumontheil/Developmental Science)

Teenagers might have a new excuse for ignoring their parent’s orders. Their brain’s ability to adopt the viewpoint of others is still budding, new research suggests.

Known as theory of mind, the ability to infer another’s perspective – emotional, intellectual, or visual – improves with age. Studies of infants, toddlers and children have documented gradual improvement in this skill with age.

In a typical test, kids watch two puppets – Sally and Anne – play with a marble, then put the marble back in a box. Anne “leaves” and Sally grabs the marble, plays with it, and then returns the marble instead to a bag.

Where will Anne first search for the marble, researchers ask the children.

“Before four, kids say she’s going to look in the bag, but after four they know she has a false belief,” says Iroise Dumontheil, a cognitive neuroscientist at University College London, UK, who led the new study.

However, brain scans suggest that a teenage mind toils harder when inferring the outlook of others, compared with adults. And a brain region implicated in theory of mind, the medial prefrontal cortex, continues to develop through adolescence, Dumontheil says.

Varied viewpoint

To see if there is a behavioural consequence of these biological changes, she and colleagues tested children, adolescents, and adults on their ability to infer the spatial perspective of another person in a simple computer game.

Test subjects – 179 females ranging in age from 7 to 27 – saw a bookshelf with a variety of different sized balls and other objects on four different rows. Some of the objects sit in front of opaque backgrounds, obscured to someone standing on the other side of the shelf, while some sit in front of a see-through background.

Participants are asked to adopt the perspective of a man standing on the other side of the shelf and move the small ball to the left, using a mouse. In a typical test, a golf ball and tennis ball are both visible to the participant, but the golf ball is obscured from the point of view of the observer. The correct response, then, is to move the tennis ball.

See images of the game here

Kids under the age of 10 moved the wrong ball in about three-quarters of trials. Children aged 10 through 13 scored marginally better, and teens answered wrong on two-thirds of trials. Adults, however, did better than 50-50, on average.

Egotistical behaviour

This, Dumontheil says, is the first behavioural evidence showing that theory of mind is still improving even through teenage years.

“You probably first need to have the idea that somebody has a different spatial perspective and then you can move onto higher thoughts,” she says.

Her team plans to next test boys and men on the same task to determine if theory of mind develops differently in males than in females.

The study’s findings may also explain teens’ sometimes callous actions.

“What is really new and amazing about this paper, is that they show that adolescents show strong egocentric behaviour that is very similar to that of young children,” says Boaz Keysar, a cognitive psychologist at the University of Chicago.

Journal reference: Developmental Science (in press)