The Sally-Ann task
To operate in a social world it’s important to have an understanding of what other people are thinking. This ability is named Theory of Mind. Theory of mind is the ability to attribute mental states — beliefs, intents, desires, emotions, knowledge — to oneself, and to others, and to understand that others have beliefs, desires, intentions, and perspectives that are different from one's own (Premack & Woodruff, 1978).
Theory of Mind is tested in the Sally-Ann test by using a false belief. The child observes Sally and Anne together, putting a marble in a basket. Sally leaves the scene and Anne moves the marble to another location. The child is asked “where will Sally look for the marble?”
If the child has developed a Theory of Mind, they will answer “in the basket” because, although the child knows that the marble has been moved, it also knows that Sally is unaware of this and will go to where she had left it.
Young children approximately 4 years old can pass the Sally-Ann test demonstrating the development of Theory of Mind. This foundation of social cognition is pivotal in social interactions hence it’s early formation. However, such a skill in my experience can often be taken for granted and Theory of Mind is replaced with cognitive bias and assumptions that can be damaging to relationships.
As adults we are put to the Sally-Ann test on a daily basis when it comes to testing false beliefs in relationships. Remember that we might learn Theory of Mind at a young age but learning about beliefs, desires, intentions, emotions and values for the self and others is a life long experience.
Reference
Premack, D & Woodruff, G (1978). "Does the chimpanzee have a theory of mind?". Behavioral and Brain Sciences. 1 (4): 515–526
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. doi:10.1016/0010-0277(83)90004-5. PMID 6681741.