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...
Christopher, who, despite being institutionalised because he is unable to look after himself, has a remarkable talent for learning and translating languages...
We predicted that Christopher should find it impossible or extremely difficult to master those parts of Epun which, ex hypothesi, contravened universal generalizations and were not describable in terms of parametric variation. If his status as a polyglot savant is accurately characterised - to a first approximation - in terms of his having an intact, or enhanced, language module in association with some impairment of his central, cognitive faculties (cf. Fodor 1983), it should follow that humanly possible (sets of) constructions provide no insuperable difficulties, whereas linguistically impossible constructions or combinations of properties, even if conceptually simple and transparent, should occasion him severe problems. However, it is plausible to assume that even the linguistically impossible could be learned via inductive reasoning - a 'central' process - provided only that his central system is not too impaired to cope. In such a situation the order in which he mastered different 'impossible' rules should be a joint function of their inherent complexity and their superficial similarity to constructions in languages that Christopher already knows...
The specific [impossible] additions [to Epun] were:
- Negative sentences, characterised by the Verb preceding the Subject, but with no negative morpheme.
- Transitive sentences in all three tenses. The past tense is characterised by the Object being moved to initial position, as well as by an overt prefix.
That is we now have the word-order patterns:
S V (O) Positive (Present and Future)
V S (O) Negative (Present and Future)
(O) S V Positive (Past)
(O) V S Negative (Past)
from "Learning the impossible: The acquisition of possible and impossible languages by a polyglot savant" by Neil V. Smith, lanthi-Maria Tsimpli, and Jamal Ouhalla