Basic numerical processes in preterms

Background. The approximate number system has been studied in neonates, animals, typical and atypical populations, but not hitherto in at risk populations, such as preterm children. The aim of the present study was to investigate, through magniutude comparisons, whether preterm birth affects the approximate number system in the same way as has been demonstrated for the exact number system. Method. Three experiments (canonical-dot comparison, random-dot comparison, Arabic number comparison) were carried out in preterm children and controls at the end of the second year of primary school (8 years of age). Results. Like controls preterms showed a Symbolic Distance Effect (SDE) in both accuracy and reaction time. Both groups exhibited a different slope for Arabic numbers compared to dots. Preterm children did not show delays in magnitude comparisons. However, the data are suggestive of slower reaction time among preterm children, calling for further investigation into their approximate representation of number. Conclusion: We hypothesize that for magnitude comparisons with symbolic (Arabic) and non-symbolic (dots) stimuli two different mechanisms are involved in both preterms and controls at 8 years of age. Further studies should be carry out in order to understand the relation between the approximate number system and the exact number system in preterms.