Abstract: It is very important to explore the origin and development of theory of mind in infants. Relative literature was reviewed to investigate the occurrence and development of theory of mind under the age of 3 years, which was from perspectives of joint attention, emotion understanding, intention understanding, desire understanding and false belief understanding. To examine the theory of mind ability in infants, researchers developed some new paradigms (e.g., nonverbal spontaneous-response tasks, verbal spontaneous-response tasks), which were adapted to infants' behavioral and cognitive ability. In addition, some studies employed the eye movement and event-related potential techniques to see infants' ability to recognize others' mental states. The findings were related to different tasks used in studies and participants' characteristics of age. We discussed some critical factors (e.g., cognitive functions, environmental factors, neural and genetic mechanisms) which may be responsible for the development of theory of mind. Finally, some important issues to be further explored in future research were proposed.

Key words: infant, theory of mind, research paradigm