A new study says that babies as young as seven months old can take into consideration the perspective of others.
This ability, called 'theory of mind', is central to human cooperation.
Lead author Agnes Kovacs, a developmental psychologist at the Hungarian Academy of Sciences in Budapest, says that the finding provides evidence for the earliest awareness in infants so far of others' perspectives, reports Nature.
The research team made the discovery by measuring a simple behaviour - how long infants stare at a scene - in experiments that did not require infants to explicitly assess others' thoughts or predict their actions.
Kovacs and colleagues showed 56 seven-month-old infants an animated cartoon in which a Smurf-like character watches a ball roll behind a rectangle placed on a table through a number of scenes.
The ball either stopped behind the rectangle and was hidden from view, or kept rolling along the table until it disappeared from the scene.
"The question now is how children revise and change their early view of the mind based on the evidence they see around them."
In some of the scenes, the 'Smurf' character watched the whole process. In others, he left too soon to see the ball's final position. For example, a ball that previously rolled behind the rectangle while the character was present would start rolling again and disappear from view after his departure. In the last scene, the rectangle dropped off, revealing no ball behind it.
The researchers found that the infants stared longer at the final scenes depicting a surprising outcome for the cartoon character when he retreated early (ball absent) than the anticipated one (ball present). Babies are thought to look longer at unexpected situations or events.
So the researchers interpret the infants' behaviour as indicating that they were surprised at the unexpected outcome, just as the cartoon character would have been. In other words, the babies seemed to process the character's viewpoint, not just their own.
The study has been published today in Science1.