At what point in development does the capacity to reason about what people think emerge? While developmental psychologists have been investigating this question for more than thirty years, the evidence they have gained so far is conflicting. On the one hand, the results of traditional, direct false-beliefs tests, which involve asking participants how a person with a false belief will act, suggest that most children under four years of age are still unaware that beliefs can be false. On the other hand, false-belief tests using indirect measures, such as, for example, looking times or anticipatory looking, suggest that even infants ascribe false beliefs to other people. As many have noted, these results pose a deep developmental puzzle.
In this work, I defend the claim that infants can already reason about beliefs. On the one hand, I argue that alternative interpretations of indirect false-belief tests fall short of the mark. On the other, I argue that the fact that young children fail direct false-belief tests can be explained in either of two ways, both of which are compatible with the claim that the capacity to reason about beliefs emerges early on. The first option is to maintain that young children fail because of performance difficulties. This type of position has been defended by other authors, but I argue that the particular proposal I put forward (which I call the processing-time account) offers a better account of the evidence. In contrast, the second option (which I call they hybrid approach) is one that, to the best of my knowledge, no one else has defended so far. This consists in arguing that direct and indirect false-belief tests recruit distinct cognitive systems, each of which can independently sustain the ability to reason about beliefs, but which follow different developmental trajectories.
After exploring these two options, I consider which is best supported by the evidence.
