Early Lexical Acquisition Research Articles

Phonological networks and systematicity in early lexical acquisition.

Infants' early words tend to be phonologically similar. This may reflect a systematic approach to early production, as they adapt newly acquired forms to fit familiar structures in the output. This "rich-get-richer" approach to phonological acquisition, known as preferential attachment in network science, proposes that new words cluster together with existing phonologically similar words in the lexicon (or network). This contrasts with recent work (e.g., Fourtassi et al., 2020) showing that the learning environment is the key predictor of learning (preferential acquisition). This study expands on previous analyses of vocabulary norm data to analyze naturalistic data, namely phonetic transcriptions of nine infants' word productions, from word onset to age 2;6. Network growth models test whether (a) acquisition is best modeled through preferential attachment or preferential acquisition, (b) the trajectory of network growth changes over time, and (c) there are any differences in network growth of adult target forms versus infants' actual productions. Results show that preferential attachment predicts acquisition of new words more convincingly than preferential acquisition: newly acquired words are phonologically similar to existing words in the network. Furthermore, systematicity becomes increasingly apparent over the course of acquisition, and infants produce their early words more systematically than we would expect from looking at target forms alone. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Supplemental Material for Phonological Networks and Systematicity in Early Lexical Acquisition

Supplemental Material for Phonological Networks and Systematicity in Early Lexical Acquisition

An ERP study on novel word learning in an immersive virtual reality context

AbstractIn this behavioral and electrophysiological study, we compare novel word learning, particularly lexical form acquisition, in an immersive virtual reality (VR) context with a picture-word (PW) association context. We also test whether inhibitory control and age of second language acquisition (L2 AoA) have modulating effects. Chinese speakers of L2 English learned two sets of German words, one set in each of the contexts. Behavioral performance from a subsequent recognition task indicated that responses to VR-learned words were faster than PW-leaned words. ERPs revealed that VR-learned words elicited more negative N100 and N200 waveforms than PW-learned words. Moreover, a significant relationship between L2 AoA and N200 amplitude was observed for VR-learned words. Taken together, the results suggest that the multi-sensory, interactive experience simulated by an immersive VR context has a positive effect on early lexical form acquisition of novel words.

Determinants of early lexical acquisition: Effects of word- and child-level factors on Dutch children's acquisition of words

AbstractPrevious research on the effects of word-level factors on lexical acquisition has shown that frequency and concreteness are most important. Here, we investigate CDI data from 1,030 Dutch children, collected with the short form of the Dutch CDI, to address (i) how word-level factors predict lexical acquisition, once child-level factors are controlled, (ii) whether effects of these word-level factors vary with word class and age, and (iii) whether any interactions with age are due to differences in receptive vocabulary. Mixed-effects regressions yielded effects of frequency and concreteness, but not of word class and phonological factors (e.g., word length, neighborhood density). The effect of frequency was stronger for nouns than predicates. The effects of frequency and concreteness decreased with age, and were not explained by differences in vocabulary knowledge. These findings extend earlier results to Dutch, and indicate that effects of age are not due to increases in vocabulary knowledge.

Contrasting lexical biases in bilingual English-Mandarin speech: Verb-biased mothers, but noun-biased toddlers.

Is noun dominance in early lexical acquisition a widespread or a language-specific phenomenon? Thirty Singaporean bilingual English-Mandarin learning toddlers and their mothers were observed in a mother-child play interaction. For both English and Mandarin, toddlers' speech and reported vocabulary contained more nouns than verbs across book reading and toy playing. In contrast, their mothers' speech contained more verbs than nouns in both English and Mandarin but differed depending on the context of the interaction. Although toddlers demonstrated a noun bias for both languages, the noun bias was more pronounced in English than in Mandarin. Together, these findings support early noun dominance as a widespread phenomenon in the lexical acquisition debate but also provide evidence that language specificity also plays a minor role in children's early lexical development.

Early lexical acquisition in the Wichi language.

This research brings new evidence on early lexical acquisition in Wichi, an under-studied indigenous language in which verbs occupy a privileged position in the input and in conjunction with nouns are characterized by a complex and rich morphology. Focusing on infants ranging from one- to three-year-olds, we analyzed the parental report of infants' vocabulary (Study 1) and naturalistic speech samples of children and their caregivers (Study 2). Results reveal that: (1) although verbs predominate in the linguistic input, children's lexicons favor nouns over verbs; (2) children's early noun-advantage decreases, coming into closer alignment with the patterns in the linguistic input at a MLU of 1.5; and (3) this early transition is temporally related to children's increasing productive command over the grammatical categories that characterize the morphology of both nouns and verbs. These findings emphasize the early effects of language-specific properties of the input, broadening the vantage point from which to view the lexical acquisition process.

Does sound structure affect word learning? An eye-tracking study of Danish learning toddlers

Previous research has shown that Danish-learning children lag behind in early lexical acquisition compared with children learning a number of other languages. This delay has been ascribed to the opaque phonetic structure of Danish, which appears to have fewer reliable segmentation cues than other closely related languages. In support of this hypothesis, recent work has shown that the phonetic properties of Danish negatively affect online language processing in young Danish children. In this study, we used eye-tracking to investigate whether the challenges associated with processing Danish also affect how Danish-learning children between 24 and 35 months of age establish and learn novel label–object mappings. The children were presented with a series of novel mappings, either ostensively (one novel object presented alone on the screen) or ambiguously (one novel object presented together with a familiar one), through carrier phrases with different phonetic structures (more vs less opaque). Our results showed two main trends. First, Danish-learning children performed poorly on the task of mapping novel labels onto novel objects. Second, when learning did occur, accuracy was affected by the phonetic opacity of the speech stimuli. We suggest that this finding results from the interplay of a perceptually challenging speech input and a slower onset of early vocabulary experience, which in turn may delay the onset of word learning skills in Danish-learning children.

Early lexical and phonological acquisition and its relationships.

Verifying likely relationships between lexical and phonological development of children aged between 1 year to 1 year, 11 months and 29 days, who were enrolled in public kindergarten schools of Santa Maria (RS). The sample consisted of 18 children of both genders, with typical language development and aged between 1 year to 1 year, 11 months and 29 days, separated in three age subgroups. Visual recordings of spontaneous speech of each child were collected and then lexical analysis regarding the types of the said lexical items and phonological assessment were performed. The number of sounds acquired and partially acquired were counted together, and the 19 sounds and two all phones of Brazilian Portuguese were considered. To the statistical analysis, the tests of Kruskal-Wallis and Wilcoxon were used, with significance level of prelace_LT0.05. When compared the means relating to the acquired sounds and mean of the acquired and partially acquired sounds percentages, there was difference between the first and the second age subgroup, and between the first and the third subgroup. In the comparison of the said lexical items means among the age subgroups, there was difference between the first and the second subgroup, and between the first and the third subgroup again. In the comparison between the said lexical items and acquired and partially acquired sounds in each age subgroup, there was difference only in the age subgroup of 1 year and 8 months to 1 year, 11 months and 29 days, in which the sounds highlighted. The phonological and lexical domains develop as a growing process and influence each other. The Phonology has a little advantage.

First translation equivalents in bilingual toddlers’ expressive vocabulary

Translation equivalents (TEs) characterize the lexicon of bilinguals from the early stages of acquisition, as reported in studies involving English and other languages in which most cross-language synonyms are dissimilar in phonological form. This research explores the emergence of TEs in Spanish-Catalan bilinguals who are acquiring two languages with many cognate words and thus languages with many cross-language synonyms with identical or similar phonological forms. Expressive vocabulary was obtained in two 18-month-old groups (monolingual and bilingual, N = 24 each) through parental report using a bilingual questionnaire. Four different vocabulary size measures were computed in bilinguals, correcting for different types of phonological overlap in words across their two languages. Bilinguals were found comparable to monolinguals in every measure except for Total Vocabulary Size (Spanish + Catalan words) in which they outscored monolinguals due to the high number of form-identical cross-language elements in their expressive vocabularies. Form-similar and dissimilar TEs accounted for less than 2% of the words produced and were only present in infants with larger vocabularies. Results support the hypothesis that phonological form proximity between words across bilinguals' two languages facilitates early lexical acquisition.

Lexical stress and phonetic processing in word learning in20‐ to 24‐month‐old English‐learning children

To investigate the interaction between segmental and supra-segmental stress-related information in early word learning, two experiments were conducted with 20- to 24-month-old English-learning children. In an adaptation of the object categorization study designed by Nazzi and Gopnik (2001), children were presented with pairs of novel objects whose labels differed by their initial consonant (Experiment 1) or their medial consonant (Experiment 2). Words were produced with a stress initial (trochaic) or a stress final (iambic) pattern. In both experiments successful word learning was established when the to-be-remembered contrast was embedded in a stressed syllable, but not when embedded in unstressed syllables. This was independent of the overall word pattern, trochaic or iambic, or the location of the phonemic contrast, word-initial or -medial. Results are discussed in light of the use of phonetic information in early lexical acquisition, highlighting the role of lexical stress and ambisyllabicity in early word processing.

Adult offer, word-class, and child uptake in early lexical acquisition

How do adults offer new words from different parts of speech? This study examined the offers in book-reading interactions for 48 dyads (parents and children aged 2- to 5-years-old). The parents relied on fixed syntactic frames, final position, and emphatic stress to highlight unfamiliar words. As they talked to their children about the referent objects, events, or scenes, they also linked new words to other terms in the pertinent semantic domain, thereby presenting further information about possible meanings. Children attended to new words, often repeating them in the next turn, and, as they got older, they too related new words to familiar terms as they talked about their referents with their parents. These data add further evidence that interaction in conversation supports the process of language acquisition.

Phonetic Specificity in Early Lexical Acquisition: New Evidence from Consonants in Coda Positions

Use of precise consonantal information while learning new words has been established for onset consonants in previous studies, which showed that infants as young as 16 to 20 months of age can simultaneously learn two new words that differ only by a syllable-initial consonant (Havy & Nazzi, 2009; Nazzi, 2005; Nazzi & New, 2007; Werker, Fennell, Corcoran, & Stager, 2002). However, there is no systematic evidence to show whether specific phonetic information in other positions within the syllable can be used while learning new words. To the contrary, Nazzi (2005) found that when tested using the same task, 20-month-olds can learn two words that differ only by a consonant, but fail to do so if they differ only by a vowel, leaving open the possibility that specificity is limited to syllable-onset positions. Accordingly, the present study evaluated 20-month-olds' ability to learn two words that differ only by a consonant in either onset or coda position. Infants succeeded for both positions, ruling out the possibility that only syllable-onset positions are specified. This further suggests that the previously reported consonant/ vowel asymmetry cannot be fully explained by syllable-onset positional effects. Additionally, the present study evaluated whether words following a predominant labial-coronal pattern would be easier to learn than less frequent coronal-labial words. It failed to obtain any such evidence.

Early Language Development in Children with Profound Hearing Loss Fitted with a Device at a Young Age: Part I—The Time Period Taken to Acquire First Words and First Word Combinations

Increasing numbers of infants and young children are now presenting to implantation centers and early intervention programs as the impact of universal newborn hearing screening programs is felt worldwide. Although results of a number of studies have highlighted the benefit of early identification and early fitting of hearing devices, there is relatively little research on the impact of early fitting of these devices on first language milestones. The aim of this study was to investigate the early spoken language milestones of young children with hearing loss (HL) from two perspectives: first, the acquisition of the first lexicon (i.e., the first 100 words) and second, the emergence of the first word combinations. Two groups of participants, one comprising 24 participants with profound HL and a second comprising 16 participants with normal hearing, were compared. Twenty-three participants in the HL group were fitted with a cochlear implant and one with bilateral hearing aids. All of these were "switched-on" or fitted before 30 months of age and half at < 12 months of age. Language data were collected using the Diary of Early Language, a procedure in which parents recorded their child's first 100 spoken single words and any word combinations produced while reaching this single-word target. Acquisition of single words was compared by using the time period (in days) taken to reach several single-word targets (e.g., 50 words, 100 words) from the date of production of the first word. The emergence of word combinations was analyzed from two perspectives: first, the time (in days) from the date of production of the first word to the emergence of the first word combinations and second, the size of the single-word lexicon when word combinations emerged. The normal-hearing group required a significantly shorter time period to acquire the first 50 (mean < 1.9 months) and the first 100 (mean < 3.9 months) words than the HL group. Although both groups demonstrated acceleration in lexical acquisition, the hearing group took significantly fewer days to reach the second 50 words relative to the first 50 words than did the HL group. Finally, the hearing group produced word combinations significantly earlier (i.e., in fewer days from production of the first word) than the HL group; however, the size of the single-word lexicon when word combinations emerged was similar for both groups. The results of this study suggest that despite fitting of a device at an early age, HL continues to impact early lexical acquisition and the emergence of word combinations. Further, similarities between the hearing and HL groups, such as the overall pattern of lexical acquisition and a lexicogrammatical link, suggest that the processes underpinning early language acquisition for hearing children and those with HL may also be similar.

The structure and nature of phonological neighbourhoods in children's early lexicons

This research examines phonological neighbourhoods in the lexicons of children acquiring English. Analyses of neighbourhood densities were done on children's earliest words and on a corpus of spontaneous speech, used to measure neighbours in the target language. Neighbourhood densities were analyzed for words created by changing segments in word-onset position (rhyme neighbours as in pin/bin), vowel position (consonant neighbours as in pin/pan/) and word-offset position (lead neighbours as in pin/pit). Results indicated that neighbours in children's early lexicons are significantly more often distinguished in word-onset position (rhyme neighbours) and significantly less often distinguished in word-offset position (lead neighbours). Moreover, patterns in child language are more extreme than in the target language. Findings are discussed within the PRIMIR framework (Processing Rich Information from Multidimensional Interaction Representations; Werker & Curtin, 2005). It is argued that early perceptual sensitivity aids lexical acquisition, supporting continuity across speech perception and lexical acquisition.

Production facilitates lexical acquisition in young children

Recent research in language acquisition argues that production plays a unique role in the acquisition of phonological and lexical representations [Fikkert. In press, LabPhonX]. In this research, we investigate the effect of production in early lexical acquisition. Twenty Dutch-learning children participated in a word-learning task, where children were taught and asked to imitate non-words. Children were then tested on their recall of the non-words, and their receptive knowledge of the non-words. Children’s performance on the two tasks was compared to whether they imitated the non-words during training, the number of times they imitated the non-words, and the accuracy of their imitations. While no effect of production during training was found on children’s receptive knowledge of the non-words, production during training was associated with children’s ability to recall the non-words. Specifically, children who produced the non-words during training were more likely to recall the non-words at test. No relationship was found between the number of times children produced the non-words during training, or the accuracy of their imitations. These results indicate that production enhances early lexical acquisition, and suggests a unique role for articulation in the formation of phonological and lexical representations.

Syntax Constrains the Acquisition of Verb Meaning

Can infants use the syntactic context of an unknown word to infer that it is a verb, and thus refers to an action? Twenty-three-month-old French infants watching a moving object were taught novel verbs, within sentences that contained only function words (e.g. “il poune par là” / “it's pooning there”). Infants then watched two instances of the object undergoing either the familiar or a novel action and were asked to point towards the screen matching the novel verb. Infants correctly pointed more often towards the familiar action. To check that they did not simply perseverate in pointing at the familiar scene, control infants were taught novel nouns on the same visual stimuli (e.g. “un poune est là”/ “a poon is here”). Contrary to verb-learning infants, noun-learning infants pointed more often to the novel action. These results confirm the hypothesis that function words, and more generally syntactic structure, support early lexical acquisition.

Influence of preterm birth on early lexical and grammatical acquisition

This study compares early grammatical and lexical acquisition in 323 preterm and 166 full-term children at 24 months. The French MacArthur-Bates parental report was employed for analysis. Gestational age and birth order showed a significant effect on vocabulary size and grammatical distribution. Preterm children showed fewer words and produced more games, routines and animal noises words. Except for the group of extremely premature children, first-born children in each gestational age group produced more words than second-born. In contrast, first-born children exhibited more predicates than second-born children. It is concluded that preterm children show delayed rather than deviant language development.

Beyond stop consonants: Consonantal specificity in early lexical acquisition

Previous research has shown that 20-month-old infants can simultaneously learn two words that only differ by one of their consonants, but fail to do so when the words differ only by one of their vowels. This asymmetry was interpreted as developmental evidence for the proposal that consonants play a more important role than vowels in lexical specification. However, the consonant/vowel distinction was confounded with another distinction, that of the continuous status of the phonemes used (discontinuous stop consonants versus continuous vowels). The present study investigated 20-month-olds’ use of phonetic specificity while simultaneously learning two words that differ by a continuous consonant. The results obtained parallel those previously found for stop consonants, confirming the original claim of an asymmetry between the roles of consonants and vowels at the lexical level.

The Role of Embodied Intention in Early Lexical Acquisition

We examine the influence of inferring interlocutors' referential intentions from their body movements at the early stage of lexical acquisition. By testing human participants and comparing their performances in different learning conditions, we find that those embodied intentions facilitate both word discovery and word-meaning association. In light of empirical findings, the main part of this article presents a computational model that can identify the sound patterns of individual words from continuous speech, using nonlinguistic contextual information, and employ body movements as deictic references to discover word-meaning associations. To our knowledge, this work is the first model of word learning that not only learns lexical items from raw multisensory signals to closely resemble infant language development from natural environments, but also explores the computational role of social cognitive skills in lexical acquisition.

Early lexical development in a self-organizing neural network

In this paper we present a self-organizing neural network model of early lexical development called DevLex. The network consists of two self-organizing maps (a growing semantic map and a growing phonological map) that are connected via associative links trained by Hebbian learning. The model captures a number of important phenomena that occur in early lexical acquisition by children, as it allows for the representation of a dynamically changing linguistic environment in language learning. In our simulations, DevLex develops topographically organized representations for linguistic categories over time, models lexical confusion as a function of word density and semantic similarity, and shows age-of-acquisition effects in the course of learning a growing lexicon. These results match up with patterns from empirical research on lexical development, and have significant implications for models of language acquisition based on self-organizing neural networks.