Reasoning what someone else is thinking constitutes intentionality, as expressed by “I think that you think that I am mistaken.” Studies involving adults have found that this understanding of the beliefs of others is limited until reaching the fifth order intentionality. However, is a higher order reasoning, such as the divining fifth order beliefs, likely to be used in everyday life? The current study devised a reasoning task in which both third order and fourth order beliefs could be used in a single task, and it identified the beliefs that are more likely to be used. A task that only used the fourth order beliefs indicated that reasoning about the fourth order beliefs was used correctly. In task where both third and fourth order beliefs could be used, however, most of the participants used the third order beliefs. These results suggest that there is some rationale for why many people use beliefs up to the third order. Reasoning about the third order beliefs impose less of a cognitive load than that about higher order beliefs. These results also suggested that the reasoning which people routinely make is related to the fact that it is not engaging with the fourth order reasoning.
