Saccadic eye movements and pause/articulation components during a letter naming speed task: Children with and without dyslexia
Al Dahhan, Noor
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Naming speed (NS) tasks that measure how quickly and accurately participants can name visual stimuli (e.g., letters) are commonly used to predict reading ability. However, the link between NS and reading is poorly understood. Three methods were used to investigate how NS relates to reading and what cognitive processes are involved: (a) changing stimulus composition to emphasize phonological and/or visual aspects (Compton, 2003); (b) decomposing NS times into pause and articulation components; and (c) analyzing eye movements during a NS task. Participants were in three groups: dyslexics (aged 9, 10), chronological-age (CA) controls (age 9, 10), and reading-level (RL) controls (aged 6, 7). We used a letter NS task and three variants that were either phonologically and/or visually confusing while subjects’ eye movements and articulations were recorded, and examined how these manipulations influenced NS performance and eye movements. For all groups, NS manipulations were associated with specific patterns of behaviour and saccadic performance, reflecting differential contributions of NS to reading. RL controls were less efficient, made more errors, saccades and regressions, and made longer fixation durations, articulation times, and pause times than CA controls. Dyslexics consistently scored in between controls, except for the number of saccades and regressions in which they made more than both control groups. Overall there were clear developmental changes in NS performance, NS components, and eye movements in controls from ages 6 to 10 that appear to occur more slowly for dyslexics. Furthermore, pause time and fixation duration were key features in the NS-reading relationship, and increasing visual similarity of the letter matrix had the greatest effect on performance for all subjects. This latter result was demonstrated by the decrease in efficiency and eye-voice span, increase in naming errors, saccades, and regressions, and longer pause times and fixation durations found for all subjects. We conclude that NS is related to reading via fixation durations and pause times; longer fixation durations reflect the greater amount of time needed to acquire visual/orthographic information from stimuli, and longer pause times in children with dyslexia reflect the greater amount of time needed to prepare to respond to stimuli.