Knowing that others have minds and being able to comprehend their thinking is one of the things that makes us human. However, scientists have yet to come to a consensus as to how early we acquire this ability. The results of a new experiment may indicate that we gain this ability earlier than previously thought:

In two experiments, the researchers had the infants [13 months] watch a series of animations in which a caterpillar went in search of food (either a red apple or a piece of cheese) that was hidden behind a screen. In some scenes, the caterpillar could see a human hand situating the food, but in others there was no hand to drop a hint. The caterpillar was either successful finding the preferred food behind the correct screen, or went behind an alternative screen with the other type of food behind it.

When the caterpillars didn’t do what one would expect — going to one screen despite seeing the human hand place the desired food behind the other — infants tended to look at the animation longer, suggesting puzzlement about the caterpillar’s actions. “This result,” says Surian, “Suggests the infants expected searches to be effective only when the [caterpillar] had had access to the relevant information.”

If the experiment’s design is sound, this means that “infants who expect agents’ behavior to be guided by such internally available information thereby exhibit an ability to attribute mental content — and this is mind reading proper, however rudimentary.”