Parafoveal processing of Arabic diacritical marks

Diacritics are glyph-like marks on letters that convey vowel information in Arabic, thus allowing for accurate pronunciation and disambiguation of homographs. For skilled readers, diacritics are usually omitted except when their omission causes ambiguity. Undiacritized homographs are very common in Arabic and are predominantly heterophones (where each meaning sounds different), with 1 version more common (dominant) than the others (subordinate). In this study the authors investigated parafoveal processing of diacritics during reading. They presented native readers with heterophonic homographs embedded in sentences with diacritization that instantiated either dominant or subordinate pronunciations of the homographs. Using the boundary paradigm, they presented previews of these words carrying either: identical diacritization to the target; inaccurate diacritization, such that if the target had dominant diacritization, the preview contained subordinate diacritization, and vice versa; or no diacritics. The results showed that readers processed the identity of diacritics parafoveally, such that inaccurate previews of the diacritics resulted in inflated fixation durations, particularly for fixations originating at close launch sites. Moreover, our results clearly indicate that readers' expectation for dominant or subordinate diacritization patterns influences their parafoveal and foveal processing of diacritics. Specifically, a perceived absence of diacritics (either in no-diacritics previews, or because the eyes were too far away to process the presence of diacritics) induced an expectation for the dominant pronunciation, whereas the perceived presence of diacritics induced an expectation for the subordinate meaning.