1. Processing Speed in Young Adults with Developmental Dyslexia: A Domain-General or
Domain-Specific Deficit?
Authors: Heeyoung Park, Linda J. Lombardino, Katelyn A. DiPietro, Denise C. Magdales,
Danielle Schoepski, Katherine E. Martin, & Lori J. P. Altmann
Purpose: The finding that dyslexic readers have processing speed deficits has led
researchers to question whether these speed deficits are domain-general or domain-specific,
but to date, no clear evidence exists to address this issue. This study is designed to
investigate whether processing speed deficits in college students with developmental
dyslexia are restricted to speed of linguistic information processing only or also affect non-
linguistic information processing.
Method: Seventeen dyslexic students were compared with seventeen age-matched normal
readers, all monolingual native speakers of English. The study had a 2 stimulus type by 2
response type design. Stimulus types included English letters as linguistic stimuli and
Korean letters as non-linguistic stimuli. Participants responded to stimuli verbally (Say the
number corresponding to a symbol) or via motor response (Press the button under the
correct response).
Results: All participants were slower responding to non-linguistic stimuli. Dyslexic readers
performed significantly more slowly on all processing speed tasks than normal readers.
There were no interactions between group and other variables. Covarying age and fluid
intelligence had no effect on these results.
Conclusions: These results suggest that dyslexic readers are significantly slower than age-
matched normal readers on both linguistic and non-linguistic processing speed tasks
regardless of response modalities. These results support the hypothesis that processing
speed deficits in dyslexia are domain-general. Findings will be discussed relative to their
applicability to reading instruction and other educational issues.