Letter Visibility and the Optimal Viewing Position Effect of Isolated Connected and Un-Connected Letters in Arabic

The present study provides a further exploration of the role of Arabic letter visibility as a possible cause of the Optimal Viewing Position (OVP) effect. We used isolated connected and un-connected Arabic letters of different shapes (basic, initial, medial, final) placed at the center of fixation (Experiment 1) and at various possible positions in isolated presentation (Experiment 2). In order to investigate whether performance in the visual identification task is modulated by letter type, we presented each of the isolated connected and un-connected letter targets in each of the eleven stimulus positions across the array to produce a mean RT (ms) for each of the letter types. Using the initial fixation paradigm enabled us to compare reaction times with correctly identified letter targets appearing in the different possible positions. The findings of the present experiments demonstrated that visual letter recognition is influenced by: (i) the isolated letters’ type (connected, un-connected), as connected letters are easier to recognize than un-connected letters; (ii) isolated letters’ shape (basic, initial, medial, final), as medial and final are harder to recognize than basic and initial letter shapes; (iii) visual field, as reading rates were longer for letter stimuli that were presented in LVF compared to RVF; and (iv) eccentricity, as letter reading rates were correlated with their eccentric placement.