According to generative linguistic theory, certain principles underlying language structure are innately given, accounting for how children are able to acquire their mother tongues (L1s) despite a mismatch between the linguistic input and the complex unconscious mental representation of language that children achieve. This innate structure is referred to as Universal Grammar (UG); it includes universal principles, as well as parameters which allow for constrained variation across languages.

As far as second language (L2) acquisition is concerned, the question arises as to whether there is a similar mismatch between input and unconscious knowledge. If L2 learners attain knowledge that goes beyond the input, this suggests that UG must play a role, providing constraints on interlanguages. At the same time, L2 learners can draw on properties of their L1 grammar. Hence, the nature and extent of crosslinguistic influence (or transfer) comes into play, raising the issue of how UG and the L1 grammar interact in determining properties of the interlanguage grammar.

Over the years, perspectives on the relationship between UG and the L1 grammar have changed and developed. This timeline will examine 25 years of research in this framework, focusing mostly on syntax and morphology. In the first decade (beginning in the 1980s), the main thrust of investigation was whether principles of UG remain accessible (fully, partially or not at all) to L2 learners during the course of acquisition and whether UG parameters can be reset. The idea that UG continues to operate in the L2 context was based on learnability arguments, which pointed to ‘gaps’ between what is exemplified in the L2 input and what learners actually come to know, unconsciously. The focus was predominantly, though not exclusively, on L2 English. Claims for the operation or non-operation of UG principles were tested experimentally. Researchers identified situations where the characteristics of the L1 and L2 were such that a principle known to operate in the L2 happened, for independent reasons, not to function in the L1. One such principle is that of Subjacency, which places constraints on wh-movement, so is relevant for wh-movement languages like English but not for so-called wh-in-situ languages like Chinese or Japanese. As for parameters, experimental research concentrated on cases where the L1 and L2 exemplified different settings of some parameter, looking for evidence of initial transfer of the L1 setting, followed by resetting. Investigation included parameters associated with Binding Principles governing the distribution of pronouns and reflexives, as well as the Pro-drop (or Null Subject) Parameter and the Verb Movement Parameter. Much of this research tried to determine whether all the consequences of a particular setting would hold together (or ‘cluster’) in the interlanguage grammar, the results being very mixed. While evidence that L2 learners demonstrate unconscious knowledge of principles of UG proved to be quite robust, evidence for parameter resetting was less compelling.

In the 1990s, emphasis shifted towards a consideration of the initial state in L2 acquisition, as well as the course of subsequent development and the nature of ultimate attainment. A broader range of L2s was investigated. Following similar trends in linguistic theory at the time, theories were couched in terms of functional categories (such as INFL and COMP) and their associated grammatical features (such as Tense and Agreement). Debate centred on whether the UG inventory of grammatical categories and features remains fully or partially accessible, whether L2 learners start off with the set of categories and features exemplified in the L1, and whether they are able to acquire categories and features that are not represented in the L1 grammar but are required in the L2. More generally, the issue of near-native competence was explored, with consideration given to which domains of grammar might never be mastered in a fully native-like manner, and the extent to which the grammars of near-native L2 speakers approximate those of native speakers. Another consideration in the domain of ultimate attainment was the issue of attrition of the L1 grammar under the influence of the L2.

In the past decade or so, there has been another shift, towards the so-called ‘interfaces’ between different modules of the grammar and how the grammar relates to other cognitive domains. The grammar includes internal components (phonology, syntax, semantics, morphology and lexicon), which must interface with each other. External domains, including discourse and pragmatics, also affect the grammar. Another external interface is that between the language processing (or parsing) system and the grammar; there is a fairly long-standing tradition which attributes L2 learners’ difficulties to parsing the L2, including problems attributable to L1 parsing principles. In general, there is active consideration of the extent to which L2 learners’ difficulties can be attributed to problems integrating material at the interfaces, especially where the L1 and L2 differ in how interface phenomena play out.

In conclusion, this timeline summarises three major themes which have recurred over time – not always with the same emphasis – in research addressing the relationship between UG and the L1 grammar. These themes are:

1. A Principles and parameters of UG

   1. A1 Motivation for UG and access to UG Principles

   2. A2 Parameters and parameter resetting

2. B From initial to final state

   1. B1 The initial state and development

   2. B2 Features and morphological variability

   3. B3 Ultimate attainment and near-nativeness

3. C Interfaces

   1. C1 Internal interfaces

   2. C2 External interfaces