On the one hand, multiple studies have shown that children with DD have fussier categorical boundaries of phonemes, and preschool speech perception has been found to be a predictor of reading, independent of phonological awareness, and speech perception of children with DD was found to be significantly delayed compared to TD children. It continues to be debated whether the whole group or only a subgroup of children with DD (or with a high risk of DD) show atypical categorical perception of phonemes. Grapheme–phoneme mapping, the backbone of reading, is only possible if phonemes can be represented categorically. Nevertheless, adults are able to recognize linguistic content in the face of variation, and we disregard linguistically irrelevant acoustical differences while attending to the phonemic differences that contrast (lexical) meaning. The same phoneme or word can drastically differ acoustically due to speakers’ anatomical structures, speaking rate, and phonetic context, etc. Categorical perception is essential for efficient speech processing since variability abounds in human speech. The essence of categorical perception is that listeners disregard lexically irrelevant acoustical differences while attending to differences of the same magnitude if they change word meaning. Typical listeners perceive such gradual changes as having distinct categories (i.e., identification shifts from pea to bee consistently at one specific step) and they discriminate the between-category stimuli better than the within-category stimuli. In categorical perception experiments, listeners are presented with stimuli that gradually change from one phonological category to another in a stepwise fashion, for instance, from pea to bee. When studying DD, speech perception has often been operationalized as categorical perception of phonemes. Ītypical speech perception has been hypothesized to underlie phonological awareness impairment among children with dyslexia. Phonological awareness difficulties, particularly phoneme awareness difficulties, are deeply rooted among people with dyslexia, and they do not disappear even after reading difficulty has been largely compensated. There is wide consensus that phonological awareness, namely, the ability to manipulate, generate or judge sound units, such as syllables, onsets, rhymes or phonemes, serves as the basis for script decoding and reading. Even though a large proportion of children at family risk (FR) do not develop dyslexia, they still perform more poorly than typically developing (TD) children on tasks such as spelling, non-word reading, and reading comprehension. There is wide agreement that dyslexia has a genetic basis, and children with a dyslexic parent have a 29–66% risk of developing dyslexia. The estimates of prevalence of dyslexia vary from 3 to 10%, depending on measures and inclusion criteria. These findings indicate that FR children are able to categorize speech sounds, but that they may do so in a more effortful way than TDs.ĭevelopmental dyslexia (DD) is an impairment of reading and spelling skills despite normal intellectual abilities and educational opportunities. For both conditions and for both groups, infant positive mismatch response (p-MMR) was elicited, and the p-MMR amplitude was comparable between the two groups, although the FR children had a later p-MMR peak than the TD children in the multiple-speaker condition. In the multiple-speaker condition, both nonwords were produced by twelve different speakers while in the single-speaker condition, single tokens of each word were used as stimuli. The children were presented with two nonwords “ giep” and “ gip” that contrasted solely with respect to the vowel. EEG response was collected in a non-attentive passive oddball paradigm from 35 TD and 35 FR Dutch 20-month-old infants who were matched on vocabulary. The current study compared the categorization of native similar sounding vowels of typically developing (TD) children and children at familial risk (FR) of dyslexia. Although allophonic speech processing has been hypothesized to be a contributing factor in developmental dyslexia, experimental evidence is limited and inconsistent.

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