We select three word segmentation models with psycholinguistic foundations – transitional probabilities, the diphone-based segmenter, and PUDDLE – which track phoneme co-occurrence and positional frequencies in input strings, and in the case of PUDDLE build lexical and diphone inventories. The models are evaluated on caregiver utterances in 132 CHILDES corpora representing 28 languages and 11.9 m words. PUDDLE shows the best performance overall, albeit with wide cross-linguistic variation. We explore the reasons for this variation, fitting regression models to performance scores with linguistic properties which capture lexico-phonological characteristics of the input: word length, utterance length, diversity in the lexicon, the frequency of one-word utterances, the regularity of phoneme patterns at word boundaries, and the distribution of diphones in each language. These properties together explain four-tenths of the observed variation in segmentation performance, a strong outcome and a solid foundation for studying further variables which make the segmentation task difficult.

One of the most popular and widely used parent report instruments for assessing early language acquisition is the MacArthur-Bates Communicative Development Inventories (MB-CDI). This study compares normative data of the Italian Words and Sentences complete form (WS-CF) and short form (WS-SF). The samples included 752 children for the WS-CF and 816 children for the WS-SF designed for children aged 18–36 months. The concordance between WS-SF and WS-CF is analyzed in a subgroup of 65 children. The results revealed strong correlations between WS-CF and WS-SF in both lexical and grammar skills as well as strong relationship between lexical and grammar skills. There was a high percentage agreement (97%) between the two forms for scores below the 10th percentile, suggesting that the two forms may be used interchangeably in order to describe vocabulary and grammatical development.

Phonological characteristics and frequencies of stems and allomorphs have been explored as possible factors causing differences in production accuracies between allomorphic forms. However, previous findings are not consistent and the relative contributions of these factors are unclear. This study investigated target and erroneous productions of the Dutch diminutive, which has five allomorphs with varying type frequencies and of which the selection depends on the phonological characteristics of the stems. Typically developing children (N = 115, 5;1–10;3) were tested on their production of real and nonce diminutives. Linear mixed effects modelling was used to analyse the data taking nonverbal IQ into account. Type frequencies of the allomorphs and differences in phonological characteristics of the stems were found to be related to differences in production accuracies between the allomorphs. However, phonological characteristics of the stems appeared to have a bigger impact, mainly due to the phonological complexity of these characteristics.

Many studies have addressed the effect of neighborhood density (phonological similarity among words) on word learning in quiet listening conditions. We explored how noise influences the effect of neighborhood density on children's word learning. One-hundred-and-two preschoolers learned nonwords varied in neighborhood density in one of four listening conditions: quiet, +15 dB signal-to-noise ratio (SNR), +6 dB SNR, and 0 dB SNR. Results showed that a high-density advantage for children under quiet listening condition was significantly reduced as noise increased. This finding implies an adverse impact of noise on long-term outcomes of word learning.

The present study examines the perceptual, linguistic, and social cues that were associated with preschoolers’ (4;11) growth in word-learning during shared book-reading and guided play activities. Small groups of three preschoolers (n = 30) and one adult were video-recorded during an intervention study in which new vocabulary words were explicitly taught. Adult use of taught words was coded for perceptual and linguistic cues and type of social interaction. Hearing taught words used in the book text and learning information about words’ meanings during play was positively associated with growth in word-learning. Adult use of words in responsive, or child-initiated, interactions was positively associated with word-learning growth in both book-reading and play, while adult-initiated use of words was negatively associated with word-learning growth in both settings.

What is the function of babbling in language learning? We examined the structure of parental speech as a function of contingency on infants’ non-cry prelinguistic vocalizations. We analyzed several acoustic and linguistic measures of caregivers’ speech. Contingent speech was less lexically diverse and shorter in utterance length than non-contingent speech. We also found that the lexical diversity of contingent parental speech only predicted infant vocal maturity. These findings illustrate a new form of influence infants have over their ambient language in everyday learning environments. By vocalizing, infants catalyze the production of simplified, more easily learnable language from caregivers.

This study investigated the role of sequential processing in spoken language outcomes for children who are deaf or hard of hearing (DHH), ages 5;3–11;4, by comparing them to children with typical hearing (TH), ages 6;3–9;7, on sequential learning and memory tasks involving easily nameable and difficult-to-name visual stimuli. Children who are DHH performed more poorly on easily nameable sequencing tasks, which positively predicted receptive vocabulary scores. Results suggest sequential learning and memory may underlie delayed language skills of many children who are DHH. Implications for language development in children who are DHH are discussed.

We investigated the association between individual differences in metaphor understanding and Theory of Mind (ToM) in typically developing children. We distinguished between two types of metaphors and created a Physical and Mental Metaphors task, echoing a similar distinction for ToM. Nine-year-olds scored lower than older age-groups in ToM as well as in the interpretation of mental, but not physical, metaphors. Moreover, nine-year-olds (but not older children) who are better in ToM are also better in interpreting mental, but not physical, metaphors. This suggests that the link between metaphor and ToM is stronger when metaphorical interpretation involves mental aspects, and it is more evident in early rather than later childhood.

Previous research in child language shows that many aspects of language acquisition are frequency-linked. This study tests whether input or usage frequency predicts the order of acquisition and accuracy of a bilingual Greek–English child's English possessives. The child was followed longitudinally from age 2;6 to 3;11. Order of acquisition was comparable to that of same-aged monolingual children. The child's usage frequency and order of acquisition were highly correlated with input frequency, while her accuracy was not. We argue that the child's already-acquired Greek possessives facilitated acquisition of English possessives, even though the child's English input and usage frequencies were lower than in monolingual English children.

The objective of this study was to examine the links between prosodic features of paternal Infant-Directed Speech (IDS) and child characteristics. Pitch variability measures were extracted from the speech samples of 50 fathers during unstructured play with their two-year-old children. Evidence for a link between child receptive language ability (measured by the Bayley Scales of Infant Development III) and fathers’ pitch variability was obtained from Multiple Hierarchical Regression. Findings support the hypothesis that fathers tailor their speech to their children. This is one of the few studies to examine the relationship between fathers’ IDS and child language ability.

We examined if and when English-learning 17-month-olds would accommodate Japanese forms as labels for novel objects. In Experiment 1, infants (n = 22) who were habituated to Japanese word–object pairs looked longer at switched test pairs than familiar test pairs, suggesting that they had mapped Japanese word forms to objects. In Experiments 2 (n = 44) and 3 (n = 22), infants were presented with a spoken passage prior to habituation to assess whether experience with a different language would shift their perception of Japanese word forms. Here, infants did not demonstrate learning of Japanese word–object pairs. These findings offer insight into the flexibility of the developing perceptual system. That is, when there is no evidence to the contrary, 17-month-olds will accommodate forms that vary from their typical input but will efficiently constrain their perception when cued to the fact that they are not listening to their native language.

Both walking abilities and pointing gestures in infants are associated with later language skills. Within this longitudinal study we investigate the relationship between walk onset and first observed index-finger points and their respectively predictive value for later language skills. We assume that pointing as a motor as well as a communicative skill is a stronger predictor of later language development than walk onset. Direct observations, parent questionnaires, and standardized tests were administered in 45 children at ages 1;0, 2;0, 3;0, and 4;0. Results show that both walk onset and early index-finger pointing predict language abilities at age 2;0, but only early index-finger pointing predicts language skills at ages 3;0 and 4;0. Walk onset seems to contribute to an initial increase in language acquisition without a sustained advantage. The predictive value of first observed index-finger points, however, is strong and lasts at least until age 4;0.

Some pronouns can refer to entities that vary widely in scope. In some cases, the referent might be a noun phrase, and in other cases it might be a whole proposition. In the cases of pronouns with a noun phrase antecedent, an already existing referent is reactivated from the preceding context. In the case of pronouns with a propositional antecedent, the referent must be reformulated. The interpretation and use of such pronouns was investigated in 150 eight-year-old children in a reading comprehension task. Experiment 1 used a referent specification task and Experiment 2 used a completion task. It was more difficult for children to process a pronoun when its antecedent was a proposition compared to a noun phrase. These results are in line with the linguistic approaches (e.g., Gundel et al., 2005) according to which processing of pronouns with a propositional antecedent is more complex and requires greater cognitive effort.

Language is conventional because word meanings are shared among different people. The present study examined Chinese infants’ understanding of the language convention that different people should generalize words in the same way. Thirteen-month-old Mandarin-speaking Chinese infants repeatedly viewed a speaker providing a novel label for a target object in the presence of a distractor object. Next, the objects changed colour and infants viewed the same speaker and a new speaker providing the label for either the different coloured target or distractor. They were also asked by both speakers to locate the correct referent of the label. Results revealed that infants expected both speakers to generalize the label to objects that belonged to the target category. This is the first evidence demonstrating that Chinese infants perceive word generalization as a form of shared convention.

In lexical development, the specificity of phonological representations is important. The ability to build phonologically specific lexical representations predicts the number of words a child knows (vocabulary breadth), but it is not clear if it also fosters how well words are known (vocabulary depth). Sixty-six children were studied in kindergarten (age 5;7) and first grade (age 6;8). The predictive value of the ability to learn phonologically similar new words, phoneme discrimination ability, and phonological awareness on vocabulary breadth and depth were assessed using hierarchical regression. Word learning explained unique variance in kindergarten and first-grade vocabulary depth, over the other phonological factors. It did not explain unique variance in vocabulary breadth. Furthermore, even after controlling for kindergarten vocabulary breadth, kindergarten word learning still explained unique variance in first-grade vocabulary depth. Skill in learning phonologically similar words appears to predict knowledge children have about what words mean.

Previous studies have demonstrated an effect of early vocal production on infants’ speech processing and later vocabulary. This study focuses on the relationship between vocal production and new word learning. Thirty monolingual Italian-learning infants were recorded at about 11 months, to establish the extent of their consonant production. In parallel, the infants were trained on novel word–object pairs, two consisting of early learned consonants (ELC), two consisting of late learned consonants (LLC). Word learning was assessed through Preferential Looking. The results suggest that vocal production supports word learning: Only children with higher, consistent consonant production attended more to the trained ELC images.

Hearing words in sentences facilitates word recognition in monolingual children. Many children grow up receiving input in multiple languages – including exposure to sentences that ‘mix’ the languages. We explored Spanish–English bilingual toddlers’ (n = 24) ability to identify familiar words in three conditions: (i) single word (ball!); (ii) same-language sentence (Where's the ball?); or (iii) mixed-language sentence (Dónde está la ball?). Children successfully identified words across conditions; however, the advantage linked to hearing words in sentences was present only in the same-language condition. This work hence suggests that language mixing plays an important role on bilingual children's ability to recognize spoken words.