A cross-linguistic study on evidentiality, source monitoring and theory of mind: comparing Turkish and English-speaking children

Some languages provide support for keeping track of one‘s knowledge or even force the speaker to mention the source of their knowledge. Turkish is one of these languages that distinctly marks the source of the speakers‘ knowledge by obliging them to specify their source when talking about past events by the help of evidential markers. English, on the other hand, does not enforce such an obligation on the speakers and the linguistic specification of the source of information is optional. Learning a language with obligatory evidential markers can also have an impact on children‘s social-cognitive development. For example, Turkish 3- to 4-year-olds have been found to be at an advantage in terms of their false-belief understanding compared to their English- and Chinese-speaking peers (Lucas et al., 2013). The aim of the current study was to investigate the contribution of evidential marker proficiency to children‘s false-belief understanding and source monitoring abilities while controlling for receptive vocabulary and short-term memory skills. We compared Turkish-speaking (N = 50, Mage = 50.1 months) and English-speaking (N = 50, Mage = 50.6 months) 42- to 59-month-olds‘ performance in three false-belief tasks. As factors that might impact children‘s performance, we measured their Source Monitoring ability, using the Mode of Knowledge Access Task (Gopnik & Graf, 1988), evidential-marker competency, using the Direct Experience and Changed State of Objects tasks (Ögel, 2007; Aksu-Koç et al., 2009), receptive vocabulary, short-term memory, and demographic factors, looking at their gender and age. Age, receptive vocabulary, and short-term memory significantly correlated with false-belief performance in both language groups (all p‘s <.05). Additionally, source monitoring performance significantly correlated with false-belief performance for Turkish-speaking children, rs(48) = .53, p < .001. Turkish-speaking and English-speaking children‘s performances were analysed together, using a generalised linear mixed effects model and by following the principle of backwards selection. The final model suggests that the language children speak, their short-term memory, and source monitoring abilities significantly predicted their false-belief understanding. In line with Lucas et al. (2013), acquiring Turkish put children in an advantageous position in terms of their false-belief understanding. These combined results, together with the results from language-specific models will be discussed in detail and the implications of these findings will be outlined. We will discuss whether this advantage was due to the mastery of evidential markers in Turkish, and to what extent a comparison of two languages with different grammatical structures might be informative.