Publications

Abstract

Continuous vector word representations (or
word embeddings) have shown success in cap-turing semantic relations between words, as evidenced by evaluation against behavioral data of adult performance on semantic tasks (Pereira et al., 2016). Adult semantic knowl-edge is the endpoint of a language acquisition process; thus, a relevant question is whether these models can also capture emerging word
representations of young language learners. However, the data for children’s semantic knowledge across development is scarce. In this paper, we propose to bridge this gap by using Age of Acquisition norms to evaluate word embeddings learnt from child-directed input. We present two methods that evaluate word embeddings in terms of (a) the semantic neighbourhood density of learnt words, and (b) con-
vergence to adult word associations. We apply our methods to bag-of-words models, and find that (1) children acquire words with fewer semantic neighbours earlier, and (2) young learners only attend to very local context. These findings provide converging evidence for validity of our methods in understanding the prerequisite features for a distributional model of word learning.

Abstract

Research on infants’ online lexical processing by Fernald, Perfors, and Marchman (2006) revealed substantial individual differences that are related to vocabulary development, such that infants with better lexical processing efficiency show greater vocabulary growth across time. Although it is clear that individual differences in lexical processing efficiency exist and are meaningful, the theoretical nature of lexical processing efficiency and its relation to vocabulary size is less clear. In the current study, we asked two questions: (a) Is lexical processing efficiency better conceptualized as a central processing capacity or as an emergent capacity reflecting a collection of word-specific capacities? and (b) Is there evidence for a causal role for lexical processing efficiency in early vocabulary development? In the study, 120 infants were tested on a measure of lexical processing at 18, 21, and 24 months, and their vocabulary was measured via parent report. Structural equation modeling of the 18-month time point data revealed that both theoretical constructs represented in the first question above (a) fit the data. A set of regression analyses on the longitudinal data revealed little evidence for a causal effect of lexical processing on vocabulary but revealed a significant effect of vocabulary size on lexical processing efficiency early in development. Overall, the results suggest that lexical processing efficiency is a stable construct in infancy that may reflect the structure of the developing lexicon.

Abstract

We report on two experiments that investigated the acquisition of the Tagalog symmetrical voice system, a typologically rare feature of Western Austronesian languages in which there are more than one basic transitive construction and no preference for agents to be syntactic subjects. In the experiments, 3-, 5-, and 7-year-old Tagalog-speaking children and adults completed a structural priming task that manipulated voice and word order, with the uniqueness of Tagalog allowing us to tease apart priming of thematic role order from that of syntactic roles. Participants heard a description of a picture showing a transitive action, and were then asked to complete a sentence of an unrelated picture using a voice-marked verb provided by the experimenter. Our results show that children gradually acquire an agent-before-patient preference, instead of having a default mapping of the agent to the first noun position. We also found an earlier mastery of the patient voice verbal and nominal marker configuration (patient is the subject), suggesting that children do not initially map the agent to the subject. Children were primed by thematic role but not syntactic role order, suggesting that they prioritize mapping of the thematic roles to sentence positions.

Abstract

Humans associate abstract words with physical stimulus dimensions, such as linking upward locations with positive concepts (e.g., happy = up). These associations manifest both via subjective reports of associations and on objective performance metrics. Humans also report subjective associations between colours and abstract words (e.g., joy is linked to yellow). Here we tested whether such associations manifest on objective task performance, even when not task-relevant. Across three experiments, participants were presented with abstract words in physical colours that were either congruent with previously-reported subjective word-colour associations (e.g., victory in red and unhappy in blue), or were incongruent (e.g., victory in blue and unhappy in red). In Experiment 1, participants' task was to identify the valence of words. This congruency manipulation systematically affected objective task performance. In Experiment 2, participants completed two blocks, a valence-identification and a colour-identification task block. Both tasks produced congruency effects on performance, however, the results of the colour identification block could have reflected learning effects (i.e., associating the more common congruent colour with the word). This issue was rectified in Experiment 3, whereby participants completed the same two tasks as Experiment 2, but now matched congruent and incongruent pairs were used for both tasks. Again, both tasks produced reliable congruency effects. Item analyses in each experiment revealed that these effects demonstrated a degree of item specificity. Overall, there was clear evidence that at least some abstract word-colour pairings can systematically affect behaviour.

Abstract

The computations involved in statistical learning have long been debated. Here, we build on work suggesting that a basic memory process, chunking , may account for the processing of statistical regularities into larger units. Drawing on methods from the memory literature, we developed a novel paradigm to test statistical learning by leveraging a robust phenomenon observed in serial recall tasks: that short‐term memory is fundamentally shaped by long‐term distributional learning. In the statistically induced chunking recall (SICR) task, participants are exposed to an artificial language, using a standard statistical learning exposure phase. Afterward, they recall strings of syllables that either follow the statistics of the artificial language or comprise the same syllables presented in a random order. We hypothesized that if individuals had chunked the artificial language into word‐like units, then the statistically structured items would be more accurately recalled relative to the random controls. Our results demonstrate that SICR effectively captures learning in both the auditory and visual modalities, with participants displaying significantly improved recall of the statistically structured items, and even recall specific trigram chunks from the input. SICR also exhibits greater test–retest reliability in the auditory modality and sensitivity to individual differences in both modalities than the standard two‐alternative forced‐choice task. These results thereby provide key empirical support to the chunking account of statistical learning and contribute a valuable new tool to the literature.

Abstract

Humans vary in almost every dimension imaginable, and language is no
exception. In this article, we review the past research that has focused on
individual differences (IDs) in first language acquisition. We first consider
how different theoretical traditions in language acquisition treat IDs, and
we argue that a focus on IDs is important given its potential to reveal the
developmental dynamics and architectural constraints of the linguistic system.
We then review IDs research that has examined variation in children’s
linguistic input, early speech perception, and vocabulary and grammatical
development. In each case, we observe systematic and meaningful variation,
such that variation in one domain (e.g., early auditory and speech
processing) has meaningful developmental consequences for development
in higher-order domains (e.g., vocabulary). The research suggests a high
degree of integration across the linguistic system, in which development
across multiple linguistic domains is tightly coupled.

Abstract

Statistical learning (SL) has been a prominent focus of research in developmental and adult populations, guided by the assumption that it is a fundamental component of learning underlying higher-order cognition. In developmental populations, however, there have been recent concerns regarding the degree to which many current tasks reliably measure SL, particularly in younger children. In the current article, we present the results of two studies that measured auditory statistical learning (ASL) of linguistic stimuli in children aged 5–8 years. Children listened to 6 min of continuous syllables comprising four trisyllabic pseudowords. Following the familiarization phase, children completed (a) a two-alternative forced-choice task and (b) a serial recall task in which they repeated either target sequences embedded during familiarization or foils, manipulated for sequence length. Results showed that, although both measures consistently revealed learning at the group level, the recall task better captured learning across the full range of abilities and was more reliable at the individual level. We conclude that, as has also been demonstrated in adults, the method holds promise for future studies of individual differences in ASL of linguistic stimuli.

Abstract

Much of Lieven’s pioneering work has helped move the study of individual differences to the centre of child language research. The goal of the present chapter is to illustrate how the study of individual differences provides crucial insights into the language acquisition process. In part one, we summarise some of the evidence showing how pervasive individual differences are across the whole of the language system; from gestures to morphosyntax. In part two, we describe three causal factors implicated in explaining individual differences, which, we argue, must be built into any theory of language acquisition (intrinsic differences in the neurocognitive learning mechanisms, the child’s communicative environment, and developmental cascades in which each new linguistic skill that the child has to acquire depends critically on the prior acquisition of foundational abilities). In part three, we present an example study on the role of the speed of linguistic processing on vocabulary development, which illustrates our approach to individual differences. The results show evidence of a changing relationship between lexical processing speed and vocabulary over developmental time, perhaps as a result of the changing nature of the structure of the lexicon. The study thus highlights the benefits of an individual differences approach in building, testing, and constraining theories of language acquisition.

Abstract

A core question in language acquisition is whether children’s syntactic processing is experience-dependent and language-specific, or whether it is governed by abstract, universal syntactic machinery. We address this question by presenting corpus and on-line processing dat a from children learning Mandarin Chinese, a language that has been important in debates about the universality of parsing processes. The corpus data revealed that two different relative clause constructions in Mandarin are differentially used to modify syntactic subjects and objects. In the experiment, 4-year-old children’s eye-movements were recorded as they listened to the two RC construction types (e.g., Can you pick up the pig that pushed the sheep?). A permutation analysis showed that children’s ease of comprehension was closely aligned with the distributional frequencies, suggesting syntactic processing preferences are shaped by the input experience of these constructions.

Abstract

Our target paper argued for the ubiquity of frequency effects in acquisition, and that any comprehensive theory must take into account the multiplicity of ways that frequently occurring and co-occurring linguistic units affect the acquisition process. The commentaries on the paper provide a largely unanimous endorsement of this position, but raise additional issues likely to frame further discussion and theoretical development. Specifically, while most commentators did not deny the importance of frequency effects, all saw this as the tip of the theoretical iceberg. In this short response we discuss common themes raised in the commentaries, focusing on the broader issue of what frequency effects mean for language acquisition.

Abstract

This review article presents evidence for the claim that frequency effects are pervasive in children's first language acquisition, and hence constitute a phenomenon that any successful account must explain. The article is organized around four key domains of research: children's acquisition of single words, inflectional morphology, simple syntactic constructions, and more advanced constructions. In presenting this evidence, we develop five theses. (i) There exist different types of frequency effect, from effects at the level of concrete lexical strings to effects at the level of abstract cues to thematic-role assignment, as well as effects of both token and type, and absolute and relative, frequency. High-frequency forms are (ii) early acquired and (iii) prevent errors in contexts where they are the target, but also (iv) cause errors in contexts in which a competing lower-frequency form is the target. (v) Frequency effects interact with other factors (e.g. serial position, utterance length), and the patterning of these interactions is generally informative with regard to the nature of the learning mechanism. We conclude by arguing that any successful account of language acquisition, from whatever theoretical standpoint, must be frequency sensitive to the extent that it can explain the effects documented in this review, and outline some types of account that do and do not meet this criterion.

Abstract

A comprehensive theory of language acquisition must explain how human infants can learn any one of the world’s 7000 or so languages. As such, an important part of understanding how languages are learned is to investigate acquisition across a range of diverse languages and sociocultural contexts. To this end, cross-linguistic and cross-cultural language research has been pervasive in the field of first language acquisition since the early 1980s. In groundbreaking work, Slobin (1985) noted that the study of acquisition in cross-linguistic perspective can be used to reveal both developmental universals and language-specific acquisition patterns. Since this observation there have been several waves of cross-linguistic first language acquisition research, and more recently we have seen a rise in research investigating lesser-known languages. This special issue brings together work on several such languages, spoken in minority contexts. It is the first collection of language development research dedicated to the acquisition of under-studied or little-known languages and by extension, different cultures. Why lesser-known languages, and why minority contexts? First and foremost, acquisition theories need data from different languages, language families and cultural groups across the broadest typological array possible, and yet many theories of acquisition have been developed through analyses of English and other major world languages. Thus they are likely to be skewed by sampling bias. Languages of European origin constitute a small percentage of the total number of languages spoken worldwide. The Ethnologue (2015) lists 7102 languages spoken across the world. Of these, only 286 languages are languages of European origin, a mere 4% of the total number of languages spoken across the planet, and representing approximately only 26% of the total number of language speakers alive today. Compare this to the languages of the Pacific. The Ethnologue lists 1313 languages spoken in the Pacific, constituting 18.5% of the world’s languages. Of these, very few have been described, and even fewer have child language data available. Lieven and Stoll (2010) note that only around 70–80 languages have been the focus of acquisition studies (around 1% of the world’s languages). This somewhat alarming statistic suggests that the time is now ripe for researchers working on lesser-known languages to contribute to the field’s knowledge about how children learn a range of very different languages across differing cultures, and in doing so, for this research to make a contribution to language acquisition theory. The potential benefits are many. First, decades of descriptive work in linguistic typology have culminated in strong challenges to the existence of a Universal Grammar (Evans & Levinson, 2009), a long-held axiom of formal language acquisition theory. To be sure, cross-linguistic work in acquisition has long fuelled this debate (e.g. MacWhinney & Bates, 1989), but only as we collect a greater number of data points will we move closer toward a better understanding of the initial state of the human capacity for language and the types of social and cultural contexts in which language is successfully transmitted. A focus on linguistic diversity enables the investigation and postulation of universals in language acquisition, if and in whatever form they exist. In doing so, we can determine the sorts of things that are evident in child-directed speech, in children’s language production and in adult language, teasing out the threads at the intersection of language, culture and cognition. The study and dissemination of research into lesser-known, under-described languages with small communities significantly contributes to this aim because it not only reflects the diversity of languages present in the world, but provides a better representation of the social and economic conditions under which the majority of the world’s population acquire language (Heinrich, Heins, & Norenzayan, 2010). Related to this point, the study of smaller languages has taken on intense urgency in the past few decades due to the rapid extinction of these languages (Evans, 2010). The Language Documentation movement has toiled tirelessly in the pursuit of documenting languages before they disappear, an effort to which child language researchers have much to offer. Many children acquire smaller and minority languages in rich multilingual environments, where the influence of dominant languages affects acquisition (e.g., Stoll, Zakharko, Moran, Schikowski, & Bickel, 2015). Understanding the acquisition process where systems compete and may be in flux due to language contact, while no small task, will help us understand the social and economic conditions which favour successful preservation of minority languages, which could ultimately equip communities with the tools to stem the flow of language loss. With these points in mind we now turn to the articles in this special issue.

Abstract

The current study investigated the role of cross-linguistic influence in Cantonese–English bilingual children's comprehension of subject- and object-extracted relative clauses (RCs). Twenty simultaneous Cantonese–English bilingual children (Mage = 8;11, SD = 2;6) and 20 vocabulary-matched Cantonese monolingual children (Mage = 6;4, SD = 1;3) completed a test of Cantonese RC comprehension. The bilingual children also completed a test of English RC comprehension. The results showed that, whereas the monolingual children were equally competent on subject and object RCs, the bilingual children performed significantly better on subject RCs. Error analyses suggested that the bilingual children were most often correctly assigning thematic roles in object RCs, but were incorrectly choosing the RC subject as the head referent. This pervasive error was interpreted to be due to the fact that both Cantonese and English have canonical SVO word order, which creates competition with structures that compete with an object RC analysis.

Abstract

Although there is strong evidence for shared abstract grammatical structure in bilingual speakers from studies of sentence production, comparable evidence from studies of comprehension is lacking. Twenty-seven (N = 27) English-German bilingual adults participated in a structural priming study where unambiguous English subject and object relative clause (RC) structures were used to prime corresponding subject and object RC interpretations of structurally ambiguous German RCs. The results showed that English object RCs primed significantly greater object RC interpretations in German in comparison to baseline and subject RC prime conditions, but that English subject RC primes did not change the participants’ baseline preferences. This is the first study to report abstract crosslinguistic priming in comprehension. The results specifically suggest that word order overlap supports the integration of syntactic structures from different languages in bilingual speakers, and that these shared representations are used in comprehension as well as production