Language Effects on Children's Nonverbal Number Line Estimations

The mental number line of children is usually assumed to be language-independent; however, this independency has not yet been studied. In this cross-cultural study, we examined the influence of language properties on a nonverbal version of the number line task in Italian- and German-speaking first graders. The essential difference between the two languages concerns the inversion property of most German multi-digit numbers (e.g., 48 -> "eight-and-forty"), whereas in Italian number-words no inversion is found. The analyses revealed two language-specific differences in the number line task: (a) Generally, the estimates of Italian children were more accurate than those of Austrian children, even when controlling for general cognitive abilities. (b) Italian children performed particularly better when inversion errors led to large estimation errors. In conclusion, these findings indicate that the organization of children's mental number line is indeed influenced by language properties even in nonverbal settings.