Comparable reading development in Bulgarian and Italian: cross-linguistic insights from a finger-tracking study

Transparent orthographies, such as Bulgarian and Italian, feature highly consistent grapheme-phoneme correspondences, enabling rapid acquisition of decoding skills. Despite belonging to different language families and using distinct scripts (i.e., Cyrillic vs. Latin), these languages provide an ideal framework to investigate whether orthographic transparency can outweigh script differences in shaping reading development. We conducted a cross-sectional study with primary school children from Grades 2 to 5 in Bulgaria and Italy. Reading performance was recorded using a novel finger-tracking technique, which allows the capture of temporal dynamics of reading in a portable, low-cost, and classroom-friendly format. Measures of reading time and text comprehension accuracy were compared across grades and languages. Developmental trajectories for both speed and comprehension accuracy showed remarkable similarity across Bulgarian and Italian, with both languages exhibiting steady improvement from grade 2 to grade 5. Our cross-linguistic results showed that reading development in primary school children follows both universal and language-specific trajectories. While broad developmental trajectories were similar, cross-linguistic differences emerged in the impact of morphological complexity, pointing to both universal and language-specific mechanisms. Our findings indicate that orthographic transparency may exert a stronger influence on early reading development than script type, even across languages from different families. The study also highlights the potential of finger-tracking for large-scale literacy research. Establishing comparable developmental benchmarks in transparent orthographies may inform cross-linguistic screening tools and early interventions.