Agrammatism––treated as a medical disorder––is defined as ‘a type of aphasia, usually caused by cerebral disease, characterized by an inability to construct a grammatical or intelligible sentence while retaining the ability to speak single words’. But there should be a different––wider––understanding of agrammatism as the regular incidence of ungrammatical forms in the speech of native speakers arising from imperfect learning.
Such incorrect forms may, of course, enter the canon willy-nilly by being sufficiently well-attested to warrant recognition as alternatives to the standard. Here, for instance, is the case of the past passive form of the verb enamor, used as an adjective (as cited in the Merriam-Webster Unabridged Dictionary Online), where the complement of is the traditional form and with the (formerly) erroneous one:
1: to inflame with love : charm, captivate — usually used in the passive with of <tourists were enamored of the town> and sometimes with with <a beautiful Indian girl with whom he was enamored — Walter Havighurst>
2: to cause (someone) to feel a strong or excessive interest or fascination — usually used in the passive with of or with < … kids who grew up enamored of both Black Sabbath and Black Flag … — Gillian Garr, Rolling Stone, 19 May 1994> <In 1999 Wall Street was enamored with anything dot-com … — Donna Seaman, Booklist, July 2003>
This particular example is relatively benign. But the wholly erroneous use of the Italian borrowing graffiti as a singular instead of graffito(an error compounded by the use of graffitis as a plural [sic!]), heard emanating this morning from the mouth of a published author on the American Public Media radio program “Marketplace Morning Report” (and noticed publicly in an ameliorative tag by the show’s literate host), can only be adjudged agrammatistically wholly beyond the linguistic pale.
It takes unusual circumstances for someone not to be a native speaker of a language. Normally, one has a mother tongue, the language of one or both of one’s parents. Unusual circumstances of another sort can produce the situation of a person speaking more than one language like a native. That is the situation in which Y-H-B has found himself all his life due to circumstances of birth and biography.
I was reminded of this conjuncture when eating lunch in a Japanese restaurant today in Beverly Hills. My habit is not to speak Japanese to waiters and waitresses in such restaurants so as not to shock them. Members of the Nipponese nation are still not entirely habituated to hearing native Japanese emanating from Caucasians, and in my case the temptation to épater le bourgeois is routinely resisted.
Speaking like a native also involves cultural paralinguistic patterns that one falls into effortlessly and almost obligatorily. It’s as if one took off one mask and put on another when speaking a different language. The Japanese cultural situation is full of behavioral peculiarities that are incumbent on one who speaks the language natively, including nods of the head, intakes of breath, ejaculations, etc. that are wholly absent from the speech situation attending American English. Withal, these features are ineluctable for someone who is a native speaker, and a trilingual one (like your Y-H-B) cannot escape them any more than a monolingual one can.
Switching to Russian, as Y-H-B had to for long stretches during a recent week-long stint at Eastern Washington University while conversing with one’s host––a man born and bred in Russia––entailed quite other sequelae. One’s mentality shifted from the habitual Anglo-American context to the poetically-inflected world of Pushkin and the Golden Age, including Krylov’s fables, which bodied forth a quite different personality.
Language is the instrument of thought, to be sure. It is also the determinant of one’s personality in many respects. A trilingual speaker must maneuver effortlessly between the worlds that a native knowledge of three languages adumbrates, and it is not always a task that a normal psyche can accommodate.