An Eye-Tracking Study on the Interword Spacing Effect in Arabic.

This study investigated interword spacing effects on eye movement during Arabic reading, focusing on the distinctive orthographic system of Arabic text. Research on Roman-script languages (e.g., English) concluded that interword spacing facilitates word identification and sentence comprehension (Rayner et al. in Vision Research 38:1129–1144, 1998, https://doi.org/10.1016/s0042-6989(97)00274-5 ; Slattery et al. in Journal of Experimental Psychology: Applied 22:406–422, 2016, https://doi.org/10.1037/xap0000104 ), whereas studies on other languages could not replicate these results (Bai et al. in Journal of Experimental Psychology: Human Perception and Performance 34:1277–1287, 2008, https://doi.org/10.1037/0096-1523.34.5.1277 ). While written Arabic uses interword spaces between words, we showed that manipulating interword spaces did not inhibit reading-related eye movements. However, we found a significant influence of interword spacing on saccadic programming. Overall, the lack of an ‘interword spacing effect’ in Arabic led us to postulate that Arabic orthography might have an important role in guiding saccades despite the absence of interword spacing. Our conclusions are also in line with the proposal that there is an independent level of abstract letter representation of Arabic which encodes allographs and letter positions (e.g., Carreiras et al. Psychonomic Bulletin & Review 19:685–690, 2012, https://doi.org/10.3758/s13423-012-0260-8 ).