The common thread of my research is an interest in the developmental, synchronic, and experimental aspects of variation in language. My research has focused on three areas:
(a) BILINGUAL LANGUAGE DEVELOPMENT. I have worked extensively on the development of syntactic knowledge in adult L2 acquisition, and particularly on the characteristics of the 'final state' attained by adults who are near-native speakers of a second language. I was the first to suggest a distinction between 'divergent' and 'incomplete' ultimate attainment, terms that have been subsequently elaborated by several researchers in the field. My more recent work is concerned with a specific feature of final-state L2 grammars, namely optionality, which is selectively found at the interface(s) between language and other cognitive domains. I have investigated the processing abilities of second language speakers in order to determine whether at least some of observed phenomena can be attributed to inefficient coordination of knowledge domains. I have compared the manifestations and consequences of optionality in L2 acquisition and in other domains of language development (e.g. first language development, language attrition and diachronic language change) and I have discovered patterns of convergence.
One domain of my developmental research is the study of changes that take place in the native language competence of speakers who have been exposed to a second language for a long time (L1 attrition). I have carried out research on syntactic attrition that sheds light on the reciprocal effects of one language on another in the bilingual's mind and eliminates the commonly held assumption that the native language is not significantly affected by learning another language.
Another developmental domain I have focused on is bilingual first language development. The questions I have addressed concern the extent to which the two simultaneously acquired systems influence each other, whether such influence is selectively found in particular areas of language competence, and why interfaces between cognitive domains are privileged 'leakage' points between grammars. In projects funded by ESRC and Leverhulme Trust with Ludovica Serratrice (University of Manchester), I worked on bilingual children acquiring different pairs of languages, with varying degrees of typological similarity, in order to determine the scope of cross-linguistic influence in bilingual development. I have also worked on the effects of age of exposure to a second language within childhood in a project funded by the Netherlands Organisation for Scientific Research (NWO) "Age effects on early child bilingualism" in collaboration with A. Hulk (University of Amsterdam), L. Cornips (Meertens Institute), Sharon Unsworth (Univ. of Utrecht/Meertens), and Ianthi Tsimpli (Aristotle University of Thessaloniki).
Most recently I have started researching the reciprocal effects of bilingualism and general cognition, bringing together the traditionally separate linguistic and psychological strands in research on bilingualism. The two domains I have focused on are attention and executive control, and cognitive aging. In a project with Sergio Della Sala and B. Treccani (Padova), I have explored the phenomenon of negative priming in speakers who were bilingual from birth, demonstrating the 'other side of the coin' of enhanced inhibitory control. I collaborated with S. Della Sala and T. Bak in several projects on effects of bilingualism on cognitive ageing.
(b) GRADIENCE, LINGUISTIC INTUITIONS AND GRAMMATICALITY JUDGMENTS. For several years I have been interested in the experimental measurement and quantification of linguistic competence. My dissertation was the first attempt to apply magnitude estimation techniques (originally developed in psychophysics) to judgments of linguistic acceptability. My subsequent work on magnitude estimation paradigms for the elicitation of grammaticality judgments has focused on the phenomenon of gradience in natural language, which I have explored with Frank Keller. This work has had ramifications both in the methodological domain (as witnessed by the increasing number of applications of magnitude estimation in different areas of linguistic research) and in the theoretical linguistic domain (e.g. computational models of gradience in language).
(c) CONSTRAINTS ON SYNTACTIC VARIATION. In a series of studies on split intransitivity (especially auxiliary selection) I have collected a wide range of data from different languages (Dutch, French, German, Italian, Japanese, and Paduan) indicating the existence of systematic lexical effects on the syntax of auxiliary selection and on some of the other manifestations of split intransitivity. My work has had an impact on linguistic typology (in the form of more descriptions of split intransitivity in a variety of languages), general linguistic theories of the lexicon-syntax interface, theories of diachronic change (especially in Romance linguistics), and developmental theories of argument structure, particularly in L2 acquisition. I have investigated the processing of auxiliary selection (with Ellen Bard, Cheryl Frenck-Mestre, Mirta Vernice Ina Bornkessel-Schlesewsky, Dietmar Roehm, and Baris Demiral) Institute for Human Cognitive and Brain Science) using eye-tracking and electrophysiological methods. I have been working on a theoretical account of variation at the lexicon-syntax interface within a formal model of grammar. In 2005-2007 I was on a British Academy Research Leave Fellowship that allowed me to work on a monograph on this topic.
Together with Caroline Heycock I conducted an AHRC-funded project investigating variation and change in the syntax of Faroese, which explored word order variation experimentally in both adult and child Faroese speakers.
KNOWLEDGE EXCHANGE AND PUBLIC ENGAGEMENT WORK
I am committed to disseminating the findings of research on bilingualism among bilingual families, schools, and policy makers. I believe that bilingualism provides much more than knowledge of two languages, and there is still too much disinformation about the advantages of growing up bilingual. I direct an information and advice service, BILINGUALISM MATTERS, that aims to disseminate accurate information about bilingualism in the community. This service started in September 2008 and currently has five branches in Scotland and Europe.
I am a member of the Developmental Linguistics Group and, more generally, of the thriving language research community at Edinburgh. More information on the activities of the Developmental Linguistics Group can be found here; information on language research in Edinburgh can be found here.