Publications

Abstract

We used eye-tracking to investigate if and when children show an incremental bias to assume that the first noun phrase in a sentence is the agent (first-NP-as-agent bias) while processing the meaning of English active and passive transitive sentences. We also investigated whether children can override this bias to successfully distinguish active from passive sentences, after processing the remainder of the sentence frame. For this second question we used eye-tracking (Study 1) and forced-choice pointing (Study 2). For both studies, we used a paradigm in which participants simultaneously saw two novel actions with reversed agent-patient relations while listening to active and passive sentences. We compared English-speaking 25-month-olds and 41-month-olds in between-subjects sentence structure conditions (Active Transitive Condition vs. Passive Condition). A permutation analysis found that both age groups showed a bias to incrementally map the first noun in a sentence onto an agent role. Regarding the second question, 25-month-olds showed some evidence of distinguishing the two structures in the eye-tracking study. However, the 25-month-olds did not distinguish active from passive sentences in the forced choice pointing task. In contrast, the 41-month-old children did reanalyse their initial first-NP-as-agent bias to the extent that they clearly distinguished between active and passive sentences both in the eye-tracking data and in the pointing task. The results are discussed in relation to the development of syntactic (re)parsing.

Abstract

Children who hear large amounts of diverse speech learn language more quickly than children who do not. However, high correlations between the amount and the diversity of the input in speech samples makes it difficult to isolate the influence of each. We overcame this problem by controlling the input to a computational model so that amount of exposure to linguistic input (quantity) and the quality of that input (lexical diversity) were independently manipulated. Sublexical, lexical, and multi-word knowledge were charted across development (Study 1), showing that while input quantity may be important early in learning, lexical diversity is ultimately more crucial, a prediction confirmed against children’s data (Study 2). The model trained on a lexically diverse input also performed better on nonword repetition and sentence recall tests (Study 3) and was quicker to learn new words over time (Study 4). A language input that is rich in lexical diversity outperforms equivalent richness in quantity for learned sublexical and lexical knowledge, for well-established language tests, and for acquiring words that have never been encountered before.

Abstract

Historically, first language acquisition research was a painstaking process of observation, requiring the laborious hand coding of children's linguistic productions, followed by the generation of abstract theoretical proposals for how the developmental process unfolds. Recently, the ability to collect large-scale corpora of children's language exposure has revolutionized the field. New techniques enable more precise measurements of children's actual language input, and these corpora constrain computational and cognitive theories of language development, which can then generate predictions about learning behavior. We describe several instances where corpus, computational, and experimental work have been productively combined to uncover the first language acquisition process and the richness of multimodal properties of the environment, highlighting how these methods can be extended to address related issues in second language research. Finally, we outline some of the difficulties that can be encountered when applying multimethod approaches and show how these difficulties can be obviated

Abstract

In developmental psycholinguistics, we have, for many years,
been generating and testing theories that propose both descriptions of
adult representations and explanations of how those representations
develop. We have learnt that restricting ourselves to any one
methodology yields only incomplete data about the nature of linguistic
representations. We argue that we need a multi-method approach to the
study of representation.

Abstract

This study investigated different accounts of children's acquisition of non-subject wh-questions. Questions using each of 4 wh-words (what, who, how and why), and 3 auxiliaries (BE, DO and CAN) in 3sg and 3pl form were elicited from 28 children aged 3;6–4;6. Rates of non-inversion error (Who she is hitting?) were found not to differ by wh-word, auxiliary or number alone, but by lexical auxiliary subtype and by wh-word+lexical auxiliary combination. This finding counts against simple rule-based accounts of question acquisition that include no role for the lexical subtype of the auxiliary, and suggests that children may initially acquire wh-word+lexical auxiliary combinations from the input. For DO questions, auxiliary-doubling errors (What does she does like?) were also observed, although previous research has found that such errors are virtually non-existent for positive questions. Possible reasons for this discrepancy are discussed.

Abstract

Studies based on naturalistic data are a core tool in the field of language acquisition research and have provided thorough descriptions of children's speech. However, these descriptions are inevitably confounded by differences in the relative frequency with which children use words and language structures. The purpose of the present work was to investigate the impact of sampling constraints on estimates of the productivity of children's utterances, and on the validity of error rates. Comparisons were made between five different sized samples of wh-question data produced by one child aged 2;8. First, we assessed whether sampling constraints undermined the claim (e.g. Tomasello, 2000) that the restricted nature of early child speech reflects a lack of adultlike grammatical knowledge. We demonstrated that small samples were equally likely to under- as overestimate lexical specificity in children's speech, and that the reliability of estimates varies according to sample size. We argued that reliable analyses require a comparison with a control sample, such as that from an adult speaker. Second, we investigated the validity of estimates of error rates based on small samples. The results showed that overall error rates underestimate the incidence of error in some rarely produced parts of the system and that analyses on small samples were likely to substantially over- or underestimate error rates in infrequently produced constructions. We concluded that caution must be used when basing arguments about the scope and nature of errors in children's early multi-word productions on analyses of samples of spontaneous speech.

Abstract

In our recent paper, ‘Semantic generality, input frequency and the acquisition of syntax’ (Journal of Child Language31, 61–99), we presented data from two-year-old children to examine the question of whether the semantic generality of verbs contributed to their ease and stage of acquisition over and above the effects of their typically high frequency in the language to which children are exposed. We adopted two different categorization schemes to determine whether individual verbs should be considered to be semantically general, or ‘light’, or whether they encoded more specific semantics. These categorization schemes were based on previous work in the literature on the role of semantically general verbs in early verb acquisition, and were designed, in the first case, to be a conservative estimate of semantic generality, including only verbs designated as semantically general by a number of other researchers (e.g. Clark, 1978; Pinker, 1989; Goldberg, 1998), and, in the second case, to be a more inclusive estimate of semantic generality based on Ninio's (1999a,b) suggestion that grammaticalizing verbs encode the semantics associated with semantically general verbs. Under this categorization scheme, a much larger number of verbs were included as semantically general verbs.

Abstract

In this study we test a number of different claims about the nature of stylistic variation at the “single-word” stage by examining the relation between variation in early vocabulary composition, variation in early language use, and variation in the structural and functional propreties of mothers' child-directed speech. Maternal-report and observational data were collected for 26 children at 10, 50, and 100 words, These were then correlated with a variety of different measures of maternal speech at 10 words, The results show substantial variation in the percentage of common nouns and unanalyzed phrases in children's vocabularies, and singficant relations between this variation and the way in which language is used by the child. They also reveal singficant relations between the way in whch mothers use language at 10 words and the way in chich their children use language at 50 words and between certain formal properties of mothers speech at 10 words and the percentage of common nouns and unanalyzed phrases in children's early vocabularies, However, most of these relations desappear when an attempt is made to control for ossible effects of the child on the mother at Time 1. The exception is a singficant negative correlation between mothers tendency to produce speech that illustrates word boundaries and the percentage of unanalyzed phrases at 50 and 100 words. This suggests that mothers whose sprech provides the child with information about where new words begin and end tend to have children with few unanalyzed. phrases in their early vocabularies.