Event‐related potentials (ERPs) to a repeating pseudoword and mismatch responses (MMRs) to five deviances were recorded at 4–5 years and compared with a previously reported follow‐up at 28 months, in subgroups with versus without familial dyslexia risk

This study investigated the neural processing of speech sounds in preschool-aged children (4–5 years) and how this processing matures from early childhood (28 months). A key focus was to determine whether familial risk for dyslexia is associated with atypical neural responses. The researchers recorded event-related potentials (ERPs) and mismatch responses (MMRs) in a large longitudinal cohort (n ≈ 150) using a multifeature oddball paradigm. This paradigm presented a repeating pseudoword (/tata/) and five different types of deviant stimuli (vowel duration, frequency, vowel identity, small frequency, and consonant duration) to assess both obligatory sound encoding and preattentive sound discrimination.

At 4–5 years, the obligatory ERPs to the standard pseudoword showed a characteristic P1–N2 pattern. The mismatch responses were primarily characterized by a mismatch negativity (MMN) followed by a late discriminative negativity (LDN). Longitudinal analysis revealed that from 28 months to 4–5 years, the P1 amplitude increased and its latency decreased, while the N2 amplitude increased. The MMN and LDN amplitudes also grew with age, and the LDN latency decreased. Notably, the positive mismatch response (P-MMR) observed at 28 months was largely absent by age 4–5, suggesting a shift toward more mature, negative-polarity discrimination responses.

Crucially, children at familial risk for dyslexia showed significantly reduced MMN amplitudes across all deviant types compared to controls. No group differences were found for the obligatory ERPs, suggesting that dyslexia-related neural deficits in this age group are specifically tied to higher-order speech discrimination rather than basic auditory encoding.

These findings provide a robust reference for typical neural speech processing during the critical preschool period. By demonstrating that reduced MMN amplitudes persist into the preschool years in children at risk for dyslexia, the study highlights the potential of the MMN as a neural marker for early identification of dyslexia risk. This research supports the phonological deficit theory, suggesting that difficulties in discriminating subtle speech contrasts may be a core neural feature of dyslexia that manifests before formal literacy instruction begins.