Objective Phonological awareness and rapid automatized naming (RAN) tasks are known to be useful to detect developmental dyslexics whose mother tongue is English. In this study, we examined the developmental changes in typically developed Japanese children for picture, digit and alternating picture-digit naming tasks.

Menthods We carried out a RAN task involving two stimuli, digits and line drawings. Digits were Arabic numerals (1–9). Sources of line drawings were chosen from a national database of vocabulary for children aged 3 to 5 years. We furthermore selected based on familiarity and established three kinds of RAN tasks in 207 elementary school children from 6 to 12 years of age. Their performance of and total articulation time for reading were measured.

Results There was a negative correlation between the articulation time and their school grade. For the digit naming task, the articulation time was significantly longer in the first graders, then stayed the same for several years, and significantly shortened again after age 10. For the picture naming task, the articulation time was significantly longer in the first graders and gradually shortened as they passed on the upper grade. For the alternating picture-digit naming task, the articulation time distributed in the time range of the picture and digit naming tasks. The changing pattern was closer to the picture naming task. Performance was good for all tasks in all grades.

Conclusion These results suggest that there is a slight difference of development between naming digits and naming pictures.