Abstract: Theory-of-mind(TOM)is an area of much concern among developmental psychologists.Disagreements still existed among researchers concerning the age at which children obtain TOM and the stages of its development.In the present study,the ‘unexpected transfer' and‘deceptive appearance' test tasks were employed in a sample of 233 3-6 years old children from three urban kindergartens,in an effort to explore when children obtain the ability of TOM and how this ability developed with children's age.The results indicated that children had developed the ability to distinguish between appearance and reality before the age of three,but they could not understand false beliefs.Four-years old children developed the understanding of both his ther own and others'false beliefs in the deceptive appearance task,and five-year old children were able to understand the false beliefs in the unexpected transfer task.Age from 4 to 5 seems to be the critical age at which children obtain theory-of-mind,but it could vary with the test tasks employed.No significant gender difference was found in children's understanding of false beliefs.

Key words: theory-of-mind, appearance-reality distinction, representational change, false belief