Eye movements are guided by morphological complexity in traditional Mongolian reading

Current research on eye movements in reading has reached a commonly accepted consensus that eye guidance—specifically, the locations of fixations within words—is determined exclusively by low-level visual features. However, this view has been challenged recently by studies in some agglutinative languages, Uighur and Finnish, where saccades have been shown to be influenced also by high-level linguistic features such as morphological complexity. The present study aimed at establishing the generalizability of the effect by extending it to an understudied written language, traditional Mongolian, with a vertical direction of text. Moreover, the current study adopted a corpus-analytic approach, which offers better ecological validity and captures wider ranges of independent variables using much larger datasets than controlled experiments. Consistent with earlier reports, our results demonstrated an influence of morphological complexity on saccades, with first fixations landing closer to the word beginning for morphologically more complex words. The morphological effect was more robust for shorter words and for less frequent words. The results suggest that Mongolian readers can decompose a saccade-target word parafoveally and modulate their saccade execution accordingly.