Dynamics of morphological processing in pre-school children with and without familial risk for dyslexia

Abstract

Difficulties in phonological processing and speech perception are associated with developmental dyslexia, but there is considerable diversity across people with developmental dyslexia (e.g., dyslexics with and without phonological difficulties). Phonological and morphological awareness are both known to play an important role in reading acquisition. Problems in morpho-phonological information processing could arguably be associated with developmental dyslexia, especially for Finnish, which is a rich morphologically language. We used MEG to study the connection between morpho-phonology in the Finnish language and familial risk for developmental dyslexia. We measured event-related fields (ERFs) of 22 pre-school children without risk and 18 children with familial risk for developmental dyslexia during a morphological task. Pairs of sentences consisting of a verb and its derived noun with the derivational suffix/–jA/and pairs of sentences consisting of a pseudo-verb and its pseudo-noun ending with the same suffix were presented to the participants. The derived nouns were also divided into correctly and incorrectly derived forms. Incorrectly derived forms contained an incorrect morpho-phonological change in the last vowel before the derivational suffix/-jA/. Both typically developing children and children at-risk for developmental dyslexia were sensitive to the morphological information, both in the case of real words and pseudowords, as shown by the sensor level analysis and cluster-based permutation tests for the responses to the morphologically correct vs. incorrect contrast. The groups showed somewhat different response patterns to this contrast. However, no significant differences were found in the between-group differences. No significant differences emerged between typically developing children and children at-risk for developmental dyslexia neither for real words nor for pseudowords. Overall, these findings suggest that pre-school children with and without risk for developmental dyslexia are already sensitive to the processing of morpho-phonological information before entering school.