The Interfunctional Relationship Between Theory of Mind and Private Speech

Background. Theory of mind is the capacity to explain and predict the behavior of others. Charles Fernyhough's dialogical model of psychological functions offers a vision of theory of mind that considers the social dimension and the importance of language, especially inner and private speech, for a person's ability to represent and manipulate multiple perspectives, and its connection to executive function. Objective. There is little direct research on Fernyhough's model. The present study addressed that gap by studying the relationship between theory of mind, private speech, and executive function (planning) in the preschool years. Design. Data were collected from a total of 86 preschool children from the Mexican state of Tlaxcala; 24 were from the first grade of preschool, 30 from the second, and 32 from the third. Their degree of internalization and their speech types (i.e., social and private) were obtained by coding their utterances during free play and during performance of a Tower of London task. Lastly, their theory of mind was assessed with a change of location and an unexpected contents task. Results. No correlation was found between children's theory of mind and their degree of internalization. However, inaudible private speech was correlated (negatively) to theory of mind performance in the third grade of preschool. Furthermore, their scores on the Tower of London task were negatively correlated with social speech and positively correlated with inaudible private speech, while the reverse was true for time of execution. Conclusion. The results suggested that the degree of internalization is a measure of the regulative function of language, not the ability to manipulate perspectives, and that it is inadequate for capturing subtle differences between performance and speech types. Role-playing conditions were recommended as better tasks for exploring the capacities for manipulating and understanding different perspectives during the preschool years.