The influence of a words’ number of letters, spatial extent, and initial bigram characteristics on eye movement control during reading: evidence from Arabic

We conducted two eye movement experiments in which we used the typographical and linguistic properties of Arabic to disentangle the influences of words’ number of letters and spatial extent on measures of fixation duration and saccade targeting (Experiment 1), and to investigate the influence of initial bigram characteristics on saccade targeting during reading (Experiment 2). In the first experiment, through the use of a proportional font, which is more natural-looking in Arabic compared to monospaced fonts, we manipulated the number of letters (5 versus 7) and the spatial extent (wide versus narrow) of words embedded in frame sentences. The results obtained replicate and expand upon previous findings in other alphabetic languages that the number of letters influences fixation durations, whereas saccade targeting (as indicated by measures of fixation count and probability of skipping and re-fixation) is more influenced by the word’s spatial extent. In the second experiment we compared saccade targeting measures (saccade amplitude and initial fixation location) in 6- and 7- letter words beginning with initial bigrams that were of extremely high frequency (ال the), relatively high frequency (لل to/for the), or beginning with the letters of the word stem. Our results showed negligible modulation of saccade targeting by initial bigram characteristics. The results also highlighted the importance of selecting the appropriate measures of initial fixation location (spatial versus character-based measures) during reading text rendered using proportional fonts.