A study of reading disability using event‐related brain potentials elicited during auditory alliteration judgments

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Abstract
Sixteen adolescent dyslexics (age range =12–18 years) and 16 similarly aged normal readers listened to spoken words and judged whether word pairs started with the same or different sounds (e.g., alliterated). Single‐syllable, high‐frequency, real‐word digitized speech stimuli were used with word pairs having a 50% chance of alliterating. Response accuracy, response latency, and event‐related brain potentials (ERPs) were recorded. Reading‐disabled participants were split into 2 groups based on performance on an auditory phonological task (Bradley Oddity Task). The 10 dyslexic participants who made errors on the task were called dysphonetics. The 6 dyslexics who made no errors were called phonetics. Normal readers responded both more accurately and faster than either reading‐disabled group. The phonetic and dysphonetic groups did not differ in accuracy or response latency. ERPs of the normal readers showed an N400 priming effect for alliterating targets. Specifically, the ERPs to the alliterating targets were significantly less negative than the ERPs to the nonalliterating targets from 250 to 450 msec post‐target onset. This effect was widely distributed bilaterally across the scalp and reached its peak over posterior sites (temporal‐central‐parietal [TCP], parietal, and occipital). The phonetic group did show a similar priming effect on the N400 for this period but only over TCP sites. The dysphonetic group did not present any priming during the 250 to 450 msec period; however, the dysphonetics did show significant priming over posterior sites between 450 and 550 msec post‐target onset. The results provide ERP evidence of abnormal phonological functioning and processing speed deficits during auditory phonological processing in reading‐disabled participants.