Last week I wrote about a segment on Foreign Accent Syndrome I saw on ABC Primetime, hoping to make two general points: one, about why the word “foreign” has come to be used as a label for the condition, and two, whether the condition relates to motor control or linguistic knowledge. This post is intended partly as an update concerning the above second point. I’ve also been contacted by a reader whose cousin is an FAS patient, and the details she provides of his case can certainly enrich the discussion.
In my earlier post, I’d suggested that the symptoms of FAS were indicative of a loss of phoneme > allophone mapping, but commenters tended toward seeing it as indicative of a loss of fine motor control. Looking back on the evidence that’s available, it seems like both (or either) could be implicated, depending on the specifics of the case.
To begin, I think a third point to add to the discussion is that, like other types of aphasia, FAS is associated with a set of possible symptoms, but no two patients present the same exact profile. Unlike other types of aphasia, FAS appears to affect only accent-level aspects of language – no telegraphic speech (loss of articles, prepositions, and/or functional affixes) and no hesitation or disfluency. Nevertheless, the exact symptoms of FAS still differ from patient to patient, because of individual differences in several dimensions (notably, the exact location and extent of the injury).
The consequence of this is that it is very hard to predict Patient B’s behavior based on the behavior of Patient A. Also, it could be that some symptoms indicate loss of motor control, while others indicate loss of linguistic knowledge. I came to the conclusions about the loss of phonological knowledge in my earlier post based only on the two subjects featured in the ABC piece, but clearly other patients (such as the Australian subject mentioned by an anonymous commenter) present symptoms more consistent with loss of motor control.
The new case I learned of this weekend has some aspects that indicate loss of motor control and some that (might) indicate an impact on linguistic knowledge. Here’s what I’ve learned so far: the patient had a sudden onset of the linguistic behavior, accompanied by frequent falling, both of which were ultimately attributed to a mild stroke. He has since recovered much function, but the FAS remains, and he has some numbness on one side.
His cousin describes in email that his FAS is marked by ending lots of words with “a”, like “milka”. (Also, he always says “Ya” rather than “yes”). This sounds like his phonological knowledge has been impacted. But these effects appear to worsen when he is tired, which suggests a motor control impact. Meanwhile, if he tries to sing or speak in a low voice, the speech symptoms disappear, which I see as another indication of phonological knowledge being impacted. In my reply, I asked the reader to see what would happen if her cousin tried to affect a British or some other accent. My reasoning here is that singing and portraying some non-natural accent might both involve an intentional type of speech control which this subject’s condition has left intact.
Here’s a summary of the kinds of evidence that might be seen in FAS patients, along with plausible interpretations.
- A scenario in which the patient has an unsystematic distribution of allophonic targets would indicate a loss of motor control. For example, suppose the patient might use any of a tap, flap, [t], [d], aspirated [t], or glottal stop (and many articulatorily dispersed variants of each) for any intervocalic /t/.
- A scenario in which the patient has a systematically novel distribution of allophonoic targets would indicate a loss or disruption of phonological knowledge. For example, suppose the patient ceases to use a flap intervocalically for /t/, but consistently uses [t] in such a context. Or maps all vowels spelled with a particular character to the same phoneme (so but and put rhyme). This is what I detected in one of the subjects on the ABC piece.
- Recovery from the condition, I still think, is consistent with both loss of motor control and loss of phonological knowledge (though the latter may seem implausible to those of us schooled with the Critical Period Hypothesis).
- Robotic, effortful speech of the type described by the anoynmous commenter is consistent more with motor control issues than with linguistic issues. I should note that again that the subjects on the ABC segment were not robotic, monotonic, or effortful in their FAS speech.
- A scenario in which the symptoms worsen under fatigue is consistent with a loss of motor control.
- A scenario in which the symptoms disappear under intentional or purposeful conditions (feigning an accent, modulating pitch, speaking a second language) is consistent with an impact on phonological knowledge.
Ultimately I think it’s possible that there is more than one type of FAS – an articulatory FAS (like the Australian subject), a phonological FAS (like the Michigan woman on the ABC piece), and a combination of the two. I may also just be wrong (neurophonology not being my training) so I welcome further input.