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Abstract:
In a recent study we demonstrated that prosodic boundaries in
natural speech are processed immediately by listeners, and guide
further sentence analysis (Steinhauer, Alter, and Friederici,
1999a). The processing of such boundaries was reflected in a large
positive going ERP component, the closure positive shift (CPS).
Here we present new data pointing to the universal characteristics
of the CPS as a physiological correlate of phonological sentence
phrasing in both listeners and readers.
The first follow-up study with written sentences had suggested
that commas elicit a qualitatively different ERP component, namely
a negative slow wave rather than a CPS (cf. CUNY'99). However, the
negative slow wave was preceded by a small CPS-like positivity, and
both components turned out to be more prominent in 11 subjects
accustomed to comma insertion at the respective sentence position.
Subjects used to deviant punctuation rules (N=13) showed both
smaller ERP effects and reduced comma susceptability in the
behavioral data. This finding seems to indicate an intra-individual
relationship between punctuation habits and comma perception. The
next reading experiment revealed that the comma-induced negative
slow wave reflected strategic expectancy-related processing due to
a garden-path condition whereas the preceding CPS-like positivity
reflected comma processing proper and was independent of the
sentence type. Thus, commas seemed to trigger a similar processing
as prosodic boundaries in spoken language, however subvocally and
depending on the punctuation rules of the respective reader
(Steinhauer et al., 1999b).
To further validate the hypothesis that commas trigger prosodic
phrasing subvocally and thus elicit a CPS-like positivity in the
ERP, we conducted another ERP experiment in which participants had
to replicate a previously heard prosodic pattern during reading.
Subjects first listened to a pure 'sentence melody' that was
stripped of any lexical information with a special filtering
procedure (PURR). Half of these prosodic patterns contained an
additional prosodic boundary. After a short pause interval,
subjects were instructed to replicate this melody during the silent
reading of a visually presented (word-by-word) sentence without
punctuation. Although the written word sequence always allowed this
sentence melody mapping, the syntactic structure of the sentence
was either compatible or incompatible with the number of prosodic
boundaries.
Both the prosodic boundaries in the pure melody and the
boundaries replicated during reading elicited CPS-like positive ERP
components which resembled those found for comma perception. Thus,
the CPS appears to be a universal on-line reflection of both overt
and covert phonological sentence phrasing independent of the input
modality.
Steinhauer, K., Alter, K., Friederici, A.D. (1999a) Brain
responses indicate immediate use of prosody in natural speech
processing. Nature Neuroscience, 2, 191-196.
Steinhauer, K., Alter, K., & Friederici, A.D. (1999b) Are
commas equivalent to prosodic boundaries? - Evidence from brain
potentials. In S. Bagnara: Proceedings of the European Conference
on Cognitive Science (ECCS), Siena, Italy, October 1999 (357-362).
Roma: Instituto di Psicologia - Consiglio Nazionale delle
Ricerche.
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