Categorical and gradient phonology: Theory meets methodology
James Myers, National Chung Cheng University
There has recently been an explosion of research on the phonological
role of phonetically gradient representations, but much of it
overlooks a central paradox. Namely, how can we distinguish gradient
and categorical phonological processes if both are realized in the
gradient medium of speech? A standard argument for gradient processes
points to systematic differences between phonological categories along
a continuous scale (e.g. incomplete neutralization). Yet since the
comparisons are between categories, such evidence at best shows only
that phonetic realizations may differ from informal intuitions
(e.g. there may be subphonemic categories). Another approach is to
note gradient phonetic shifts caused by shifts in some other gradient
variable (e.g. lexical frequency). Though valid, this approach has
limited usefulness, since most grammatical variables are categorical
(e.g. featural, prosodic, or morphological contexts).
In this talk I discuss a different way to distinguish categorical and
gradient processes, building on the assumption that the
categorical/gradient distinction should correlate with other
distinctions. The case study concerns variable t/d-deletion in
English, which has been claimed to apply both lexically and
postlexically (Guy 1991a,b). One argument for this claim is that final
/t/ is more likely to delete in monomorphemic (M) words like "mist"
(deletion can apply either lexically or postlexically) than in
regularly inflected (R) words like "missed" (deletion can only apply
postlexically, after -ed suffixation). Another argument is that
word-internal context affects deletion in M words more than in R
words, while word-external context affects both equally.
Phonetic research has shown that t/d-deletion involves gradiently
overlapping gestures (Browman and Goldstein 1990). However, since
lexical processes are generally assumed to be categorical, M words
should also sometimes surface with /t/ categorically deleted, though
such outputs need not neutralize with words like "miss", without
underlying /t/, given the possibility of subphonemic categories (Myers
1995).
The methodological challenge is that the distributions for
categorically t-less and gradiently t-reduced M tokens cannot be
observed separately, since the specific path followed by any given M
token is unpredictable. Fortunately, there is a recently developed
statistical technique for inferring the most likely locations of
overlapping distributions, and it is easily implemented in R, the free
statistics package. This technique finally offers the opportunity for
a conclusive test of the predictions of Myers (1995). Namely, both M
and R words should share a component reflecting gradient t-reduction,
but M words should show an additional distribution reflecting
categorical t-deletion. Moreover, the first component should be
equally sensitive to word-internal and word-external context, while
the second should only be sensitive to word-internal context.
Back to the
Phonology Workshop home page