EN
The main purpose of this study was to check to what extent the performance of 3-year-olds in the false-belief task (FBT) could be improved by concomitant application of four factors found to be significant in a meta-analysis by Wellman et al. (2001). These factors are: 1) deceptive motive for the transformation; 2) the child's participation in changing the object's location; 3) the salience of the protagonist's mental state; 4) the salience of real-world state of affairs. An additional aim was to check whether the susceptibility to experimental manipulation was dependent on the level of executive control (EC), and on the syntactic aspect of language development (SL). The study included 44 children with a mean age of 3.5 years. FBTs involving three locations and three control questions were used. The performance of experimental group was significantly above chance and higher than that of control group. Susceptibility to experimental manipulation was not dependent on either EC (Dimensional Change Card Sort) or SL (embedded clause syntax). However, a comparison of performance of younger vs. older 3-year-olds showed that only the older group was susceptible to experimental manipulation. This may suggest that not only the executive demands, but also conceptual ones, could be responsible for the difficulties in FBT performance, experienced by younger children. .