Language Development and Disorders (LDD): research projects

Research studies

The Acquisition of Auxilaries in Early Child Language.


Children's early language is obviously not adultlike, but many of the most influential theories in the field of language acquisition claim that relatively abstract adultlike grammatical knowledge underlies even very early speech. A recent constructivist theory, the usage-based model, challenges these claims.  The model proposes that children's early utterances are based around simple patterns for quite a long period of development (patterns such as "Where's the X?" and "it's a Y"; where X and Y stand for a number of items that can slot into the frames).  A substantial body of evidence is emerging to support this idea.  However, very little work has emerged to test the claims that the usage-based model makes about the process by which children move from the relatively simple frames to a more abstract, adultlike knowledge of grammatical rules and categories, or to compare its predictions with those of more traditional accounts.  The aim of this study was to provide the first direct test of these predictions.  By creating a new unique corpus of data from older children (2;8-3;6) and by focussing in detail on one grammatical category (the auxiliary) we aimed to test the predictions of current theories regarding (1) the sequence of acquisition of the auxiliary category, and (2) the role of the language that the child hears and how this interacts with the language acquisition mechanism.  To date, a large amount of elicited production data has been analysed and we are currently in the process of carrying out a number of analyses based on our new naturalistic dataset.

Duration of the project


Funding body

ESRC RES-23-0673

Members of the project

Professor Anna TheakstonPrincipal investigator
Dr. Caroline RowlandCo-investigator

How children learn auxiliary verbs is central to research on language development for two reasons. First, whether an auxiliary verb should be present in any given sentence, and the position in which it should occur, is determined by complex rules relating to the grammar and meaning of the sentence. This means that a deeper understanding how children learn the properties of auxiliaries should lead us towards a better explanation of language acquisition in general. Second, it is relatively easy to identify patterns of correct auxiliary verb use and errors since there are relatively few auxiliary verbs, and they are easily identifiable, even when omitted (Where he going? has an omitted auxiliary 'is').

This combination of theoretical complexity and methodological simplicity has attracted much work, but there is little agreement about how auxiliary verbs are learned. This is primarily due to a lack of good quality data and to differing methodological techniques. This project collected a unique sample of naturalistic data to resolve some of the controversies and test some of the current theories of auxiliary acquisition. In addition, elicited production data was collected for specific high and low frequency auxiliaries.

Current generativist theories of auxiliary verb acquisition argue that there is a role for some innately pre-specified knowledge, but that an extensive amount of learning of the rules of auxiliary verb use in any given language is required. Until recently, there were few non-generativist theories of auxiliary verb acquisition but Tomasello’s (2000) usage-based model provides a well-specified account of an acquisition mechanism, from which it is possible to derive predictions about auxiliary verb development. This theory contends that the basis of children’s early linguistic productions is a learned knowledge of utterance-meaning pairings based on item-specific constructions.

A large corpus of naturalistic data was transcribed and coded, and the elicitation tasks were successful. The main findings were that:
• Children’s acquisition of auxiliary verb 'be' (ie is/are/am/was/were) follows different developmental patterns in declarative statements than in questions. The forms 'is' and 'are' are used differently, children make more errors with 'are', and different types of errors occur in different sentence constructions.
• Children acquire auxiliary verb 'do' (ie do/does/did) and the modals can/can’t and will/won’t in declarative statements before questions. There are few differences between positive and negative forms in acquisition, with both occurring with non-inversion (e.g. What the man can do?) and auxiliary doubling errors (e.g. What can the man can't do?). There may be some generalisation between auxiliary forms in declaratives.

These findings lend some support to usage-based approaches to acquisition in that different auxiliary verb forms appear to be learned to some extent independently, with little evidence of generalisation between constructions. In contrast, there is little support for generativist models of acquisition; specifically for the claims that auxiliary verb 'do' poses more problems for children than other auxiliary verb forms, that children generalise between 'is' and 'are', or that negative forms are prone to auxiliary doubling errors while positive forms are not.


Accurate descriptions of language use, in particular auxiliary verb use, in non-clinical populations are important as baselines against which to assess language disorders. The outcomes of this project, along with our previous and ongoing research, provide information about how the language children hear impacts on their language use, with potential applications in clinical interventions.The research has been disseminated at conferences and via journal publications (eg Journal of Speech Language and Hearing Research) which inform the work of non-academic researchers and practitioners, especially speech and language therapists working with children with language difficulties.


How do children learn grammatical constructions? Keynote address Northwest Educational Psychology Continuing Professional Development Network conference, Chorley, December 2008

“Why do you don’t like cheese?” : patterns of error in children’s positive and negative declaratives and questions Invited seminar, University of Lincoln, March 2011.

The development of the auxiliary category in 3-year old children learning English Paper presented at the 31st Boston University Conference on Language Development, Boston, USA, 2006.