Variation and assimilation in German - Institut für Phonetik

558 COENEN, ZWITSERLOOD, AND BOÈLTE
The gestural model, which elegantly deals with partial assimilation,
could explain our data from Experiment 1 if residual traces of the original
gesture were present in the signal. In fact, Nolan (1992) showed that such
traces can be utilised by listeners even when these traces are not detectable
with electropalatography. Although we tried hard to produce a complete
segment change, we have no way of knowing whether such traces were
present in our segments. Given the close correspondence between
articulation and perception in this model, it could explain our ndings
even in the absence of acoustic traces.
How does underspecication fare in the light of our results? The theory
correctly predicts no effects when changes are phonologically illegal. But
other aspects are problematic for underspecication. Firstly, underspecied
representations should not bother with context to license a
change in surface form. But we clearly nd that a licensing context is a
prerequisite. Second, how would underspecication handle our results for
assimilation of voice? One could argue for [voiced] as the unspecied
feature, allowing voiced segments to be devoiced. But it remains unclear
how underspecication could handle the quantitative differences between
regressive place and progressive voice assimilation. Also somewhat
problematic for this theory are the null effects for legal progressive place
assimilation in viable context. It is not easy to think of rules which would
block place assimilation at word onset, while allowing it elsewhere. As
argued earlier, such rules cannot generally apply to word onsets, because
we nd effects for voice at this position.
So, underspecication alone cannot explain the results. Additional
mechanisms have to be operative. There are two proposals in the
literature: inference and anticipation. Gaskell and Marslen-Wilson
(1996) assumed a process of phonological inference that evaluates the
contextual appropriateness of assimilations. Lahiri (1995) argues against
such an inference process. Based on data from an experiment on German,
she proposed a combination of underspecifed lexical representations with
an anticipation mechanism. In her unviable contexts, assimilated words led
to longer latencies than unchanged words. This she interprets as an
anticipation effect. The presence of a change creates the expectancy that a
segment with particular features (e.g., labial or velar) should come next.
This anticipation is not satised in unviable contexts. Such an anticipation
explanation was also provided by Otake et al. (1996), for Japanese, by
Lahiri and Marslen-Wilson (1991), for nasalised vowels in English, and by
Gow (2000), for cases of assimilation in which the original place feature is
not completely neutralised. Our data are hard to reconcile with Lahiris
underspecication-cum-anticipation view. First, it predicts no difference
between unchanged and legally changed words in viable contexts. But we
do nd such differences. Moreover, the view predicts slower responses in