Cross-format integration of numberwords and Arabic digits

Cross-format integration between number words and Arabic digits is currently emerging as under-researched but promising candidate predictor of successful math development. This work will establish whether cross-format integration is a reliable longitudinal predictor of math development in primary school. It will investigate the developmental trajectory of crossformat integration and the role of linguistic factors for cross-format integration. Critically, cross-format integration of single- and two-digit numbers will be investigated in English and German, two languages that have similar number words, but differ in the critical characteristic of inversion of tens and units (34 is thirty four in English, but vierunddreißig - four and thirty in German). In a two-year longitudinal study, children in the UK and in Austria will be followed from school entry until the end of Grade 2. In a second, cross-sectional research strand, children in grades 2 and 4 and adults in the two languages will participate in detailed assessments of numerical processing comprising of experimental and neurophysiological (EEG) measures. Together, the programme of work will provide a more complete picture of the relationship between the processing of number words and of Arabic digits and might thus contribute towards identifying risk factors for the development of math difficulties.

Numeracy is important for academic and professional success. This research project investigated the development of a fundamental principle of numeracy, the link between number words and Arabic numbers, with the aim to identify potential risk factors for low numeracy. Children entering primary school need to shift from using mainly spoken number words (e.g., 'twenty-three') to being able to write down the correct multi-digit Arabic strings (e.g., '23') upon hearing spoken number words. Importantly, the transcoding rules of reading and writing multi-digit numbers depend on the language spoken. English and German have very similar number word systems, with the critical difference that German requires the inversion of decade and unit numbers ('23' is 'dreiundzwanzig'). In different longitudinal and cross-sectional project parts, we tracked the development of transcoding and its relevance for math performance cross-linguistically in German- and English-speaking samples from Grade 1 to adulthood. We found that development of multi-digit number transcoding poses language-specific as well as language-independent challenges: As predicted, we observed a high amount of inversion-related errors in German-speaking first graders, while such errors were exceptional in English. Interestingly, however, the two language groups showed a similar amount of inversion errors for teens, where inversion applies not only to German, but also to English ('14' - 'fourteen'). Thus, for the first time we could show that inversion poses problems to English-speaking children as well. Across languages, accuracy rates in transcoding were strongly related to number syntax. For instance, transcoding of syntactic zeros (e.g., 109) was significantly more accurate than transcoding of lexical zeros (e.g., 190). In a number matching task, German-speaking children, and even adults were significantly slower to reject inverted number distractors than English speakers. Our findings thus extend current knowledge by revealing linguistic effects long after transcoding rules are mastered, even in adulthood. Still, transcoding plays a similarly crucial role in the development of arithmetic skills during the first three years of primary school in languages with and without number word inversion. Another foundational aspect of number processing is cross-format integration of Arabic digits and spoken number-words, allowing effortless switching between formats. In a series of EEG-experiments, we identified neural correlates of cross-format integration, but only when numerical processing was required, and only in adults, but not in 9-year-olds. We conclude that associating visual-Arabic digits and spoken number words to an integrated representation of number requires a considerable amount of experience with numbers in their different formats. The findings of the current project are highly informative for theory and practice as they impressively show the long-term relevance of ensuring profound comprehension and automatization of crucial aspects of number (transcoding, cross-format integration) in in order to foster young childrens arithmetic development.