Pre-GenSLA: 1960s-1970s In the late 1960s-early 1970s researchers observed that the language and errors of L2 learners were not random but systematic and evidence of rule-governed behaviour. From this observation researchers proposed the concept of
interlanguage which refers to the language system used by L2 learners that contains interacting linguistic aspects of both the L1 and L2. This system theory regarding the interlanguage suggests that L2 learners have mental grammars that can be described with rules and principles. Therefore, an extra component, such as the UG which consists of innate domain-specific linguistic knowledge, is needed to account for these POV properties. Another important element of these features for GenSLA research is interpretability.
New Populations: 2000s Onwards By the 2000s it was generally accepted that adult SLA differed from child L1 acquisition in process and typical outcomes and there was evidence for adult accessibility in at least some properties of UG. This motivated GenSLA theory to shift focus from questions just about UG accessibility and specific features to describing and explaining variation at group and individual levels. This casts doubt on the
critical period hypothesis (CP) that age is the determining factor in convergent language acquisition, another rich area of debate in GenSLA research With respect to child L2 acquisition, it was hypothesized that if child and adult L2 learners follow the same developmental path this would call into question the claims made by some GenSLA researchers that differences between L1 and L2 learners are due to the inaccessibility of UG. This is because in GenSLA child L2 learners under the age of 7 to 8 are hypothesized to have access to UG. Thus, if the developmental paths of child and adult L2 learners overlap significantly it is likely that the basis of difference is the shared experience they have with their L1. If, however, if they follow different developmental paths this would seem to support the claim that adult L2 learners do not have access to UG; their learning must instead be due to other factors. Finally, in multilingual acquisition, if it were shown that adult L2 learners can transfer POS properties only available from their L2 to their L3 or L4 etc. this could also be used to cast doubt on the CP hypothesize. In addition, there has been a movement towards examining children's L2 acquisition. The study of child SLA is argued to be an important way of examining both child L1 acquisition and adult L2 acquisition. Unlike adults, children acquiring an L2 are considered to have full and direct access to Universal Grammar, and are typically more successful at retainment of the L2 and reaching a state of fluency. Some scholars have argued that examining child L2 acquisition is an essential tool in solving the debate over adult access to UG Most recent work on child L2 acquisition within generative framework has focused on the following 3 major issues: • L1 influence in child L2 acquisition, • The availability of functional categories (emphasis on the acquisition of tense-agreement and tense-aspect), • Morphological variability. ==Access Theories==