From early on, infants show a preference for infant-directed speech (IDS) over adult-directed speech (ADS), and exposure to IDS has been correlated with language outcome measures such as vocabulary. The present multi-laboratory study explores this issue by investigating whether there is a link between early preference for IDS and later vocabulary size. Infants’ preference for IDS was tested as part of the ManyBabies 1 project, and follow-up CDI data were collected from a subsample of this dataset at 18 and 24 months. A total of 341 (18 months) and 327 (24 months) infants were tested across 21 laboratories. In neither preregistered analyses with North American and UK English, nor exploratory analyses with a larger sample did we find evidence for a relation between IDS preference and later vocabulary. We discuss implications of this finding in light of recent work suggesting that IDS preference measured in the laboratory has low test-retest reliability.

Variegation – the presence of more than one supraglottal consonant per word – is a key challenge for children as they increase their expressive vocabulary toward the end of the single-word period. Here we consider the prosodic structures of target words and child forms in English, Finnish, French, Japanese and Mandarin to determine whether children learning these languages respond similarly to the challenge or instead differ in ways related to the phonological structure of the adult language. Based on proportional occurrence of each structure, we find that the word forms of children learning Mandarin and Japanese show more variegation than do those of children learning the European languages, although their target words do not; proportions of reduplication, consonant harmony and single-consonant words also differ by language. We conclude that experience with the structure of the language – and thus representation, as well as immature articulatory skills – shapes children’s responses to variegation.

This study explores the possibility that early word segmentation is aided by infants’ tendency to segment words with repeated syllables (‘reduplication’). Twenty-four nine-month-olds were familiarized with passages containing one novel reduplicated word and one novel non-reduplicated word. Their central fixation times in response to these as well as new reduplicated and non-reduplicated words introduced at test showed that familiarized reduplicated words were segmented better than familiarized non-reduplicated words. These results demonstrate that infants are predisposed to segment words with repeated phonological elements, and suggest that register-specific words in infant-directed speech may have evolved in response to this learning bias.

This article presents an autosegmental analysis of the development of pitch phonology in Swedish and Japanese, which mark both lexical accent and phrasing through movements in fundamental frequency (F0). Predictions that follow from the autosegmental model are tested against spontaneous production data from child Japanese. In support of the analysis that lexical pitch accent and phrasal intonation are acquired as separate sequences of tonal features, the falling and rising slopes of F0 contours are shown to develop independently. The late emergence of the phrase-initial rise is attributable to the allophonic surface realisation of the low boundary tone. Moreover, developments in contour shapes are characterised by demarcated emergence of F0 turning points that are aligned with specific segments, providing further support for the view that pitch phonology is acquired as strings of tonal units associated with segments and prosodic constituents.

Children use pronouns in their speech from the earliest word combinations. Yet, it is not clear from these early utterances whether they understand that pronouns are used as substitutes for nouns and entities in the discourse. The aim of this study was to examine whether young children understand the anaphoric function of pronouns, focusing on the interpretation of the pronoun it in English-speaking children at 1;6 and 2;0. We tested whether adults and children would prefer to look at a previously introduced vs. novel visual object depending on the argument form (it, the + noun, a + noun, or silence). Results demonstrate that, like adults, two-year-olds understand that it refers to a previously introduced referent. There is no evidence that this knowledge is established in children at 1;6. This suggests that some time between 1;6 and 2;0 children come to understand that it refers to a highly accessible referent introduced in the prior context.

Although it has been often hypothesized that children learn to produce new sound patterns first in frequently heard words, the available evidence in support of this claim is inconclusive. To re-examine this question, we conducted a survival analysis of word-initial consonant clusters produced by three children in the Providence Corpus (0 ; 11–4 ; 0). The analysis took account of several lexical factors in addition to lexical input frequency, including the age of first production, production frequency, neighborhood density and number of phonemes. The results showed that lexical input frequency was a significant predictor of the age at which the accuracy level of cluster production in each word first reached 80%. The magnitude of the frequency effect differed across cluster types. Our findings indicate that some of the between-word variance found in the development of sound production can indeed be attributed to the frequency of words in the child's ambient language.

This study investigates whether developmental dyslexia involves an impairment in implicit phonological representations, as distinct from orthographic representations and metaphonological skills. A group of adults with dyslexia was matched with a group with no history of speech/language/literacy impairment. Tasks varied in the demands made on (implicit) phonological representations versus metalinguistic analysis/manipulation, and controlled the contribution of phonological versus orthographic representations by including both a segmental and an equivalent suprasegmental (nonorthographic) version of each task. The findings show a dissociation between metaphonological skills and implicit phonological representations, with the dyslexic group impaired in metaphonological manipulation skills in both segmental and suprasegmental tasks, but not in implicit knowledge of phonological contrasts.