Speed and accuracy of dyslexic versus typical word recognition: an eye-movement investigation.

Richard Kunert,Christoph Scheepers

doi:10.3389/fpsyg.2014.01129

Abstract

Developmental dyslexia is often characterized by a dual deficit in both word recognition accuracy and general processing speed. While previous research into dyslexic word recognition may have suffered from speed-accuracy trade-off, the present study employed a novel eye-tracking task that is less prone to such confounds. Participants (10 dyslexics and 12 controls) were asked to look at real word stimuli, and to ignore simultaneously presented non-word stimuli, while their eye-movements were recorded. Improvements in word recognition accuracy over time were modeled in terms of a continuous non-linear function. The words' rhyme consistency and the non-words' lexicality (unpronounceable, pronounceable, pseudohomophone) were manipulated within-subjects. Speed-related measures derived from the model fits confirmed generally slower processing in dyslexics, and showed a rhyme consistency effect in both dyslexics and controls. In terms of overall error rate, dyslexics (but not controls) performed less accurately on rhyme-inconsistent words, suggesting a representational deficit for such words in dyslexics. Interestingly, neither group showed a pseudohomophone effect in speed or accuracy, which might call the task-independent pervasiveness of this effect into question. The present results illustrate the importance of distinguishing between speed- vs. accuracy-related effects for our understanding of dyslexic word recognition.

Highlights

It is estimated that developmental dyslexia is a reading impairment affecting between 5 and 17.5% of the population (Shaywitz, 1998; Vellutino et al, 2004)
In the presented study we focused on the two most widely reported problems in dyslexic word recognition—a phonological core deficit combined with a general deficit in processing speed (Vellutino et al, 2004; Swanson and Hsieh, 2009)
As we shall discuss in detail later, the lexical decision paradigm is poor at distinguishing between a dyslexic speed deficit and a dyslexic accuracy deficit1

Summary

Introduction

It is estimated that developmental dyslexia is a reading impairment affecting between 5 and 17.5% of the population (Shaywitz, 1998; Vellutino et al, 2004). Evidence for a phonological core deficit in dyslexic readers is based on a variety of experimental paradigms (cf Vellutino et al, 2004), especially the LDT (e.g., Bergmann and Wimmer, 2008; Lavidor, 2011; Zeguers et al, 2011; Mahé et al, 2012). Since timing of responses is under their control, they could decide to respond quickly (at the expense of making more errors), when presented with “difficult” stimuli such as infrequent words or “word-like” non-words This would result in an apparent deficit in the quality of phonological representations while speed of access to those representations is impaired

Results

Discussion

Conclusion