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

This is the famous STO paper (Smith-Tsimpli-Ouhalla) reporting the amazing unique case of Christopher, a polyglot savant, who had a remarkable talent for learning and translating languages.
Christopher, who, despite being institutionalised because he was unable to look after himself, had a remarkable talent for learning and translating languages. Given a previously unseen passage in any of some sixteen or so languages, Christopher read it - fluently but not flawlessly - in English.
Christopher was born on 6th January, 1962); tests of his non-verbal IQ gave the following results: Raven's
Matrices - 75; Wisc-R, UK - 42, 67, 52 (test administered on three different occasions; 'Draw a Man' - 40; Columbia Greystone Mental Maturity Scale - Score 68, Mental age 9.2, IQ 56 (test administered at age 29.2).
Tests of his verbal IQ on the other hand gave results in the normal range: Wisc-R, UK - 89, 102, 98; in the Gapadol Reading Comprehension Test he scored at the maximum level, indicating a reading comprehension age of 16.10; in the Peabody Picture Vocabulary Test his scores for different languages were: English - 121, German - 114, French - 110, Spanish - 89.