Sally-Anne test
The Sally-Anne test is a psychological test, used in developmental psychology to measure a person's social cognitive ability to attribute false beliefs to others (Wimmer & Perner, 1983). In 1988, Leslie and Frith repeated the experiment with human actors (rather than dolls) and found similar results.

# Test description
The experimenter uses two dolls, "Sally" and "Anne". Sally has a basket; Anne has a box. Experimenters show their subjects (usually children) a simple skit, in which Sally puts a marble in her basket and then leaves the scene. While Sally is away and cannot watch, Anne takes the marble out of Sally's basket and puts it into her box. Sally then returns and the children are asked where they think she will look for her marble. Children are said to "pass" the test if they understand that Sally will most likely look inside her basket before realizing that her marble isn't there.
Normal children under the age of four, along with most autistic children (of all ages), will answer "Anne's box," seemingly unaware that Sally does not know her marble has been moved.
In the Baron-Cohen study of theory of mind in autism, 61 children were tested with "Sally" and "Anne".
After introducing the dolls, the child's ability to name those dolls was tested (the Naming Question).
After this, Sally takes a marble and hides it in her basket. She then leaves the room and goes for a walk. When Sally is away, and therefore unknown to her, Anne takes the marble out of Sally's basket and puts it in her own box. Sally returns and the child is asked the key question: 'Where will Sally look for her marble?' (the Belief Question).
Two control questions were then askedthe Reality Question and the Memory Question.
The Reality question is "Where is the marble really?". This is to make sure the child had paid attention to the transfer of the marble from the basket to the box.
The Memory question is "Where was the marble in the beginning?". This is designed to make sure the child had not forgotten where Sally had left her marble.
For the children to succeed in this task they have pass the 'Belief Question'. The children have to show that Sally has her own beliefs which may not match up with how things really are. The correct response to the 'Belief Question' is to indicate Sally's basket. This will show that the child knows that Sally believes the marble is in her basket. The incorrect response is to point to Anne's box (Sally doesn't know that Anne hid her marble in the box).

# Interpretation
Children who pass the test (presumably) understand that there are two different sets of beliefs:
- their own beliefs, based on what they have personally seen, heard, remembered, imagined, reasoned, etc., and
- the beliefs of others, based on what they have seen, heard, etc..
Children who pass this test are believed to have the following mental capacities:
- to recognize that other people have perceptions/feelings/beliefs/thoughts/etc. different from their own;
- to recognize that others may not know everything they themselves know, and vice versa;
- to "mind-read" (or "mind-guess") other people's thoughts and feelings;
- and to predict (or even interfere with) other people's third-party relationships.
Those children who fail the test are said by some psychologists to lack a "theory of mind." (In this context, "mind" refers to psychological processes such as perception, belief, thought, or memory.) However, failing the Sally-Anne test does not mean that an individual has no awareness of mental states: great apes and very young children, who typically fail the test, nonetheless show other sophisticated social behaviors (such as empathy).

# Great apes and other monkeys
Since other great apes are not known to have a human-like theory of mind, it is assumed that it evolved after our ancestors diverged from other great apes. Suddendorf has suggested that this occurred with H. erectus (dating from 1.8 mya). Current research has failed, however, to disprove conclusively a theory of mind in other great apes and some new world monkeys outside the family of great apes, as for example the capuchin monkeys.

# Criticism
Strictly speaking, the scenario presented in the test does not give sufficient information to determine Sally's expectations about the location of the marble.  For example, it is not said whether Sally and Anne had previously discussed possible locations for the marble.  Thus "I don't know" is, in a sense, the most correct answer.
A positive answer can be reached only by making assumptions about the unstated parts of the situation.  There are many possible sets of assumptions that could be made, and the small number of likely answers means that the test cannot adequately distinguish between many of the possible assumptions.  Furthermore, the categorisation of responses into "passes" and "failures" throws away most of that information.  There are several ways to pass, and vastly more ways to fail.
These problems make the test of limited use as a diagnostic tool.  The standard interpretation of the test identifies a particular stage in the most common pattern of development of social understanding, but it is misleading when applied to subjects who are not following the standard pattern.  This is of particular concern with autistics, who are commonly diagnosed as lacking a theory of mind on the basis of "failing" the test.