| |
Abstract:
Speakers must consider many things when preparing a sentence.
First and foremost, they must decide what content words to say
(they say 'dog' when they mean dog and 'cat' when they mean cat).
Speakers must also decide between syntactic alternatives and
whether to include optional material. For example, if a speaker
decides to use a sentence complement (SC) structure, she must then
decide whether to include the optional 'that' ("The secretary
remembered (that) you were out for the day").
Ferreira and Dell (1998) examined what might underlie the
decision to include or exclude optional material. One explanation
relies on the ambiguity avoidance model of speech production, which
presumes that speakers are motivated by the need to create
sentences that are easy to comprehend. In the context of SC
sentences, the insertion of 'that' can alleviate the inherent local
syntactic ambiguity, and therefore make the sentence easier to
comprehend. Ferreira and Dell's study investigated 'that'-insertion
in SC sentences and found that speakers did not reliably produce
more 'that's when the sentence was locally ambiguous.
The current study investigates this issue further, including an
analysis of the speakers' prosody. Speakers read and memorized
sentences like "The secretary remembered you/I were out for the
day." After a short delay, speakers recalled the sentences to a
listener. Sentences either contained a temporary ambiguity
(...you...) or were syntactically unambiguous because of case
marking (...I...). In addition, we compared verbs that plausibly
take 'you' as a direct object (e.g., "remembered") with verbs that
do not plausibly take 'you' as a direct object (e.g., "learned").
Utterances were recorded analyzed for 'that'-insertion and for
prosody (duration of the verb in milliseconds and pitch drop over
the verb in hertz). These prosodic factors were chosen because
Beach (1991) found that these cues affected listeners'
interpretations of DO/S ambiguities - verb lengthening and greater
pitch drop pushed listeners toward S-comp interpretations.
Results replicated Ferreira and Dell regarding 'that'-insertion
- speakers inserted 'that' equally often in all ambiguous and
unambiguous conditions (an average of 31%, with no reliable effects
or interactions). However, prosodic analyses of sentences without a
'that' showed a main effect of ambiguity on verb duration
(ambiguous: 404 ms, unambiguous: 368 ms, F(1,13) = 9.15, p<.01)
and a main effect of direct object plausibility on pitch drop
(plausible: 15.8 Hz, implausible: 7.1 Hz, F(1,12) = 9.65, p<
.01) and no interactions. When the data were normalized into
Z-scores and added together (duration data + pitch data), there was
only a main effect of ambiguity (ambiguous: 0.266, unambiguous:
-0.347, F(1,14) = 12.03, p <.01) and no interactions. Thus,
speakers were more likely to produce prosodic cues that signal an
SC when the SC was ambiguous but not when it was unambiguous.
The data suggest that speakers provide prosodic cues to
disambiguate temporary syntactic ambiguities, but do not
consistently disambiguate material by adding optional lexical items
(e.g., 'that'). Moreover, listeners may differentially signal
syntactic and semantic ambiguities via the prosodic cues of
duration and pitch drop. However, combined analyses suggest that
only syntactic ambiguity is signaled prosodically.
References
Beach, C. M. (1991). The interpretation of prosodic patterns at
points of syntactic structure ambiguity: Evidence for cue trading
relations.
Journal of Memory and Language,
30, 644-663.
Ferreira, V. S., & Dell, G. S. (1998). Syntactic and lexical
choices in language production: What we can learn from 'that.'
Paper presented at the Eleventh Annual CUNY Conference on Human
Sentence Processing, New Brunswick, NJ.
|
