Indexical and symbolic referencing: what role do they play in children's success on theory of mind tasks?

Numerous measures have been employed in the last 17 years to assess theory of mind (ToM). The literature reports marked variability in the age at which children succeed on these measures. To account for this variability, researchers have provided explanations ranging from cognitive shifts and voids to the inability to understand the language of the tasks or to social/pragmatic considerations, all of which tell us little if anything about the internal mechanism underlying ToM. The main purpose of this paper is to provide a comprehensive theoretical account of children's success and the discrepancies found across different ToM tasks. We test the hypothesis that children's understanding of ToM is sensitive to the basic elements of language, that is, to whether the language is indexical or symbolic. Support for this account was found in the analysis of selected test protocols in four published studies of ToM, and new data collected from 53 children (4--6 years) which showed that a higher percentage of children succeeded on tasks with a high ratio of indexical to symbolic references than on tasks with a high ratio of symbolic to indexical references. There was also a main effect of age with older children succeeding at higher rates on both tasks than younger children. Our findings suggest that indexical representation can afford ToM understanding in 4-year-olds, but is not sufficient for a more mature ToM. The latter requires symbolic representation that was demonstrated by the majority of 5--6-year-olds.