Learning the impossible: the acquisition of possible and impossible languages by a polyglot savant. Lingua

We report on the case of a polyglot savant (Christopher) who has a remarkable talent for learning and translating languages. Building on previous work which had established both the range of languages at Christopher's command and the extent to which his linguistic knowledge was integrated into his cognitive ability, we taught him two new languages for which we controlled the input. We had two main aims: the first was to test the hypothesis (within one version of the Principles and Parameters framework) that parameter resetting is not an option available to the second language learner; the second was to accrue further evidence for or against Fodor's modularity hypothesis and cast light on the possible range of interactions between linguistic and 'central ' cognitive processes. The languages chosen were Berber, an Afro-Asiatic language spoken in North Africa, and Epun, an invented language deliberately devised to contain constructions which violated universal grammatical principles. In Christopher's acquisition of Berber we gleaned evidence from a variety of phenomena, including word order, null subjects, that-trace effects, wh-island violations and cliticisation, that his learning was conditioned by a combination of transfer effects from English and principles of UG, rather than by the effect of parameter resetting. In Christopher's acquisition of Epun we began with a core of 'normal ' constructions, designed to make him feel at home in the new language, and then proceeded to investigate a range of impossible constructions, both structure-dependent and structure-independent. In the former case, we concentrated on negative sentences, constructed with no overt negative morpheme. and past-tense sentences which involve unattested and putatively impossible word-orde