Brain Imaging & Linguistics

[Lise Menn, Linguistics, CU Boulder]

It's a good point about the semantics. There's also the
task variables I noted on the Info-childes network; if you want to see
waht I said there, let me know.  Lise Menn
On Tue, 28 Jan 1997, Colin Harrison wrote:

>         I wonder how many of you have read Jaeger et al's piece in Language
> (72.451-97) about areas of the brain that are activated during past tense
> formation in English.  I understand that it's been quite a hit in some
> parts of the linguistic world, and it's certainly to be praised for its
> methodological rigor and the honesty of the authors. I am convinced that
> this sort of experimentation ought to represent a significant direction for
> future research (some of which I hope to be doing soon myself).  The thing
> is, the experimenters interpret their results as showing that regular
> inflections are processed differently than irregular inflections, but I
> don't see that their theoretical conclusions follow from their data due to
> at least two major confounds.  I wanted to put these ideas out to the rest
> of you Funknetters and see what y'all think.
>         First up, semantic discrepancies between Jaeger et al.'s word lists
> represent a significant confound.  The two lists of interest are the cue
> sets from which subjects had to form regular and irregular past tenses
> (sets 3 and 4).  Jaeger et al. note that overall, the irregular past forms
> require more cortical activation than the regulars, and conclude that this
> is because they are not associated with an on-line rule system, and hence
> require more attention and greater resource devotion (p.487).  But if you
> look at the meanings involved, a rather different explanation seems at
> least plausible.
>         Each list comprises 46 tokens.  Of these, the regular past list has
> just nineteen (41%) that are unambiguously human physical activities,
> involving limb movement.  The irregular list shows a much higher proportion
> of human physical activities, 33 of the 46 tokens (73%).  This looks like a
> significant difference to me!  Might not the greater cortical activation
> noted in the irregular condition be a result of more widespread somatic
> activation as an intrinsic part of the meaning of the verbs, rather than
> anything to do with their morphosyntactic regularity?  There is ample
> evidence emerging from imaging studies (follow up for instance the work of
> Hanna and Antonio Damasio), that the comprehension of words that are
> connected with any kind of somatic experience involves activation in some
> of the same areas as the instantiation of the experience itself.  So, the
> meaning of a verb such as "walk" will involve indirect activation of the
> somato-sensory circuits necessary to walk, plus all those more peripherally
> involved in the experience of the activity etc.
>         Jaeger et al's results look as if they represent disconnected
> activation patterns, but their results were not so neat and clean at first:
> they needed to "wash" a fair amount of "random" noise from their charts
> until they arrived at something resembling the neat, discrete pictures they
> presented.  They are completely open about the normalising proceedures they
> follow, and it's all there in black and white for anyone who wants to
> examine it more closely than I have.  My concern is, it's not unlikely that
> they could have "washed" out the evidence of simmilar somatic activation
> from the regular list, but the somatic activation in the irregular list
> would have been too large to remove in this way, leaving behind different
> activation patterns based not on algorithmic versus non-algorithmic
> processing (Jaeger et al's conclusion), but rather based on the semantic
> category of the verbs in each list.
>         Secondly, even if we dismiss the first objection, the experimental
> design itself assumes the conclusion.  That is, subjects in the test
> conditions were performing an algorithmic task at the behest of the
> examiner: "given x (a verb stem form), produce y (the past tense of the
> same verb)."  It is not clear to me that information about brain activation
> during a predictable (and probably pretty boring) two-minute algorithmic
> task has any relevance to brain activation during production of similar
> forms when one is engaged in meaningful speech.  In order to equate these
> two types of processing, you have to begin with the assumption that
> speakers inflect verbs according to an algorithmic procedure during on-line
> discourse production - exactly the kind of process whose centrality to
> natural language production is disputed!
>
> What do you think?
>
>
> Colin Harrison
> Dept. of Linguistics
> Rice University
> Houston TX 77030
> USA
>