Referential ambiguity resolution in sentence comprehension: A developmental study measuring eye movements and pupil dilation

The present study investigated whether adults and 5-and 6-year-old children could incrementally resolve referential ambiguity of adjective-noun phrases in Japanese. Using a visual world paradigm, the experiment examined whether the proportion of participants' gaze on the referent and their pupil dilations were affected by the timing of disambiguation (pre-nominal adjective or noun). The results indicated that the proportion of the adults' gazes showed a reliable effect of the timing of disambiguation, but this was not found in the results from the children. The 6-year-olds' pupil dilation data showed larger pupil dilations in the adjective disambiguation condition than in the noun disambiguation condition. This suggests that the 6-year-olds also incrementally resolved the referential ambiguity. Furthermore, the adults showed a disambiguation effect, with larger dilations for the noun disambiguations than for the adjective disambiguations. No significant differences were observed in the data from the 5-year-olds. These results suggest that the 6-year-olds and the adults were able to resolve referential ambiguities incrementally, but that the 6-year-olds' eye movement control was not as fully developed as the adults'. In addition, the results suggested that pupil dilations could be a complementary measure of on-line sentence processing. That would be especially advantageous when experimental participants are young children.