Implicit theory of mind in infancy: an experimental study based on an unexpected-identity task

Research on infant theory of mind shows that children in their second year of life can attribute false beliefs to others. In this study, we investigated infants’ ability to ascribe false beliefs concerning the identity of an object. To this end, we presented children (n=70) aged 20-24 months (Mage = 22.10 months, SD = 1.44) with a novel “unexpected identity” task – adapted from a test devised by Butterfill and Apperly (2013) – and used eye-tracking to assess their performance. Each child individually viewed two videos featuring a double-sided wolf/grandmother puppet and an actress. In one video (the true-belief condition), the actress was initially shown both puppet’s identities; in the other video (the false-belief condition), she was initially only made aware of the wolf identity. The videos were presented in counterbalanced order. We assessed whether the children reacted differentially to the two videos, given that under the true-belief condition their expectations would be violated by the actress’ reaction. We thus measured two target variables: overall duration (in seconds) of fixations on the agent's face, and mean frequency of visits to the agent's face. A repeated-measures analysis of covariance (ANCOVA), including age as a covariate, showed that regardless of trial sequence (true-belief scenario first, false-belief scenario first), children gazed at the agent for longer intervals and more frequently under the true-belief condition. This finding supports the view that children attribute false beliefs to others from an early age.