Naming fluency in dyslexic and nondyslexic readers: Differential effects of visual crowding in foveal, parafoveal, and peripheral vision

Abstract

Reading fluency is often indexed by performance on rapid automatized naming (RAN) tasks, which are known to reflect speed of access to lexical codes. We used eye tracking to investigate visual influences on naming fluency. Specifically, we examined how visual crowding affects fluency in a RAN-letters task on an item-by-item basis, by systematically manipulating the interletter spacing of items, such that upcoming letters in the array were viewed in the fovea, parafovea, or periphery relative to a given fixated letter. All lexical information was kept constant. Nondyslexic readers’ gaze durations were longer in foveal than in parafoveal and peripheral trials, indicating that visual crowding slows processing even for fluent readers. Dyslexics’ gaze durations were longer in foveal and parafoveal trials than in peripheral trials. Our results suggest that for dyslexic readers, influences of crowding on naming speed extend to a broader visual span (to parafoveal vision) than that for nondyslexic readers, but do not extend as far as peripheral vision. The findings extend previous research by elucidating the different visual spans within which crowding operates for dyslexic and nondyslexic readers in an online fluency task.

Keywords:

• Rapid automatized naming
• Visual crowding
• Dyslexia
• Eye movements

We thank Margaret Snowling for her useful comments on previous versions of the manuscript.

FUNDING

The first author has received funding from the European Community's Seventh Framework Programme [FP7/2007-2013, under grant agreement number ELDEL PITN-GA-2008-215961-2]. The second author is funded by the Coleg Cymraeg Cenedlaethol (www.colegcymraeg.ac.uk).

Notes

¹Gaze durations are thought to reflect production processes up to and including activation of phonological codes (Griffin, 2001) and are closely yoked with naming times (e.g., Jones et al., 2008).