Historically, it was thought that young children first understand false belief at around 4–5 years of age, when they pass verbal tests such as the change-of-location (Sally-Anne) and change-of-contents (Smarties) tests (see Wellman, Cross, & Watson, 2001, for a review). However, several non-verbal tasks have since clarified that children under 4 years of age do have an understanding of false belief.

What is the critical pitfall of classic false belief tasks?

     There is a mixed controversy as to why children under 4 years fail the classic Sally-Ann task. Baillargeon (2010) suggested that the Sally-Ann task imposes other cognitive demands in addition to simply representing other’s false belief. To successfully pass the Sally-Ann task, participants have to undergo three cognitive processes (i) the false-belief representation process; (ii) the response-selection process and (iii) the response-inhibition process. Let’s examine these three processes step-by-step:

(i) the false-belief representation process: children must represent the agent’s false belief. When we ask whether children understand others’ false belief, this is the cognitive process that we really want to probe.
(ii) the response-selection process: children have two representations: the true belief (their own representation) and the false belief (the agent’s representation). When asked the test question, children must selectively access their own representation of the agent’s false belief.
(iii) the response-inhibition process: Again, children have two representations of belief. When selecting a response, children must inhibit any prepotent tendency to answer the test question based on their own knowledge, as their own representation differs from that of the agent.

Thus, given the cognitive load of this task, failure of the Sally-Ann task cannot simply be interpreted as a lack of false belief.

Here I would like to review a non-verbal spontaneous false-belief task, which only requires the false-belief representation process.

Active helping paradigm (Buttelmann, Carpenter, and Tomasello, 2009)
     Eighteen-month-old Infants were presented with the following scenario:
In front of them, there are two boxes (pink on the left and yellow on the right) and one experimenter. The experimenter put a toy in the box on the left and either exited the room through the door (false-belief condition) or stayed in the room (true-belief condition). During his absence or presence, another experimenter transferred the toy into the box on the right. In the false-belief condition, the first experimenter came back to the room. He falsely believed that the toy was in the original location because he did not see the toy being moved. In contrast, when the experimenter remained in the room in the true-belief condition, he truly believed that the toy was in the second location.
Regardless of the condition, the experimenter attempted to open the original box. Infants were allowed to freely move while watching the scenario. Here is the question: did infants help the experimenter open the original box, or did they open the other box, knowing the toy was in there?
Results showed that in the false-belief condition, more infants opened the second box containing the toy as opposed to the original box which the experimenter falsely believed contained the toy. On the contrary, in the true-belief condition, more infants helped the experimenter open the original box. In the false-belief condition, infants assumed that he truly wants to get the toy, but does not know that the toy was transferred into the other box. Thus, they were motivated to help the experimenter by showing him where the toy was really located. In the true-belief condition, infants assumed that he knew that a toy is no longer in that box, and that he continues to open the box for some other reason or motivation. Thus, they help him open that box.

Summary
The results of this experiment confirm that there are other methodologies to elicit children’s understanding of false belief, and that this can be done non-verbally, thus potentially studying younger children.

Reference

Wellman, H. M., Cross, D., & Watson, J. (2001). Meta‐analysis of theory‐of‐mind development: The truth about false belief. Child development, 72(3), 655-684.

Baillargeon, R., Scott, R. M., & He, Z. (2010). False-belief understanding in infants. Trends in cognitive sciences, 14(3), 110-118.

Buttelmann, D., Carpenter, M., & Tomasello, M. (2009). Eighteen-month-old infants show false belief understanding in an active helping paradigm. Cognition, 112(2), 337-342.