Understanding of another person’s wrong belief requires explicit representation of the wrongness of this person’s belief in relation to one’s own knowledge. Three to nine year old children’s understanding of two sketches was tested. In each sketch subjects observed how a protagonist put an object into a location x and then witnessed that in the absence of the protagonist the object was transferred from x to location y. Since this transfer came as a surprise they had to assume that the protagonist still believed that the object was in x. Subjects had to indicate where the protagonist will look for the object at his return. None of the 3–4-year old, 57% of 4–6-year old, and 86% of 6–9-year old children pointed correctly to location x in both sketches. Of the many cases where 4–6-year olds made an error they failed in only about 20% to remember the initial location correctly. As a test of the stability of children’s representation of the protagonist’s wrong belief the sketches continued with a statement about the protagonist’s intention to either deceive an antagonist or truthfully inform a friend about the object’s location. Independent of age, of those children who correctly thought that the protagonist would search in x, 85% of the time they also correctly thought that he would direct his antagonist to location y and his friend to location x. This shows that once children can represent a person’s beliefs they can constrain their interpretation of this person’s stated intentions to the person’s beliefs. In a more story-like situation another group of children had to infer a deceptive plan from the depiction of a goal conflict between two story characters and one character’s expedient utterance. At the age of 4–5 years children correctly judged this utterance as a lie only 28% of the time while 5–6-year olds did so 94% of the time. These results suggest that around the ages of 4 to 6 years the ability to represent the relationship between two or more person’s epistemic states emerges and becomes firmly established.
Wimmer, H., & Perner, J. (1983). Beliefs about beliefs: Representation and constraining function of wrong beliefs in young children’s understanding of deception. Cognition, 13(1), 103-128.