Deaf Readers' Lack of Implicit-Prosody Effects
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Deaf Readers' Lack of Implicit-Prosody Effects Mari Kobayashi Edson T. Miyamoto ([email protected]) Kaori Sato University of Tsukuba College of Japanese Language and Culture Tsukuba, Ibaraki 305-8572 Japan Abstract written words or the way that working memory handles longer phrases could be the crucial factor. According to the implicit prosody hypothesis, prosodic contours usually associated with spoken utterances are Ideally, one would like to compare how silent reading implicitly imposed on sentences read in silence, thereby is conducted with and without implicit prosody, but this affecting the interpretation of ambiguous constructions is not easily achieved (but see Miyamoto, Nakamura & (Fodor 2002). Some of the strongest evidence support- Takahashi, 2004, Experiment 2; Slowiaczek & Clifton, ing this hypothesis manipulated the prosodic length of segments (Hirose 2003). However, such manipulations 1980, on the possibility of eliminating inner speech dur- also increase the number of characters in the critical ing reading through simultaneous articulation of non- words, thus the results may not reflect the influence of sense syllables). prosodic factors but rather how perceptual mechanisms We report the results of a fragment completion study and working memory handle written words with larger with deaf readers of Japanese, which indicate that they number of characters. If so, such results should be repli- cable even with readers who have low ability in handling are not sensitive to the manipulations used by Hirose phonological information. We report experimental re- (2003). Therefore, the results support the proposal that sults suggesting that deaf readers are not sensitive to the effects are related to prosodic contours rather than such length manipulations. This is compatible with the working memory or perception, under the assumption assumption that prosodic contours, and not some other type of length measure, are at stake, therefore providing that deaf readers are less likely to be affected by implicit further support for the implicit prosody hypothesis. prosodic contours during silent reading. Key words: sentence comprehension, deaf, implicit Ambiguous relative clauses in Japanese prosody, Japanese, clause boundary, ambiguity Japanese is a head-final language with subject-object- verb order. There are no overt markers to indicate the Introduction beginning of embedded clauses, therefore words in the According to the implicit prosody hypothesis (IPH), embedded clause are commonly taken to be part of the prosodic contours usually associated with spoken utter- matrix clause (but see Venditti, in press, for prosodic ances are implicitly imposed on sentences read in silence, cues in speech). For example, readers usually inter- thereby affecting the interpretation of ambiguous con- pret the fragment in (1) as a single clause (`Morishita structions (Fodor, 2002). The effects of such implicit truly trusted the medicine', where Morishita is a proper prosodic contours have been explored recently both in name).1 formal syntax as well as in the language processing liter- ature. A number of empirical results have been reported (1) Morishita-ga shinyaku-o kokorokara shinyooshita on implicit prosody effects, but many of them have not PN-nom medicine-acc truly trusted addressed alternative explanations. The most common type of manipulation increases the length of constituents However, when a noun such as yuujintachi-ni `friends- in order to show that longer phrases are more likely to dat' is read after `trusted', it is clear that this verb is modify the farther of two potential attachment sites (see part of a relative clause modifying the noun (relative Fodor, 2002, for a summary of the relevant studies). clauses in Japanese precede the noun they modify) and One of the strongest sets of results providing support readers have to decide where the beginning of the relative for the IPH has used ambiguous relative clause construc- clause is likely to be. The two most common alternatives tions in Japanese (Hirose, 2003; see also Hirose & Kakei, are the late opening interpretation, in which the relative 1998). However, as in other similar studies, the ma- clause starts after the direct object, and the early open- nipulation used leads to unavoidable side-effects such as ing interpretation, in which the relative clause starts at longer words and phrases measured in number of char- the direct object `medicine-acc' as schematically repre- acters, and not just longer in terms of prosodic length sented in (2a, b) (Mazuka & Itoh, 1995; see Hirose, 2003, 1 as was intended. This is a problem because it allows for The nominative case marker (nom) is usually used for the possibility that it is not implicit prosody that is driv- subjects, the accusative marker (acc) for direct objects and ing the effect. Instead, perceptual processes for longer the dative marker (dat) for indirect objects. 1629 on the early versus late opening labels; also Inoue, 1990; Implicit prosody and relative clauses Miyamoto, 2002, for related experimental results). In Experiment 1 in Hirose (2003), native Japanese speak- (2) a. Late opening ers read fragments as in (3a, b) in silence, and were Morishita-ga shinyaku-o [RC kokorokara . asked to complete them into full sentences. The frag- PN-nom medicine-acc truly ments containing conjoined names were more likely to be completed with early opening interpretations than b. Early opening single-name fragments (Hirose, 2003, who also reports Morishita-ga [ shinyaku-o kokorokara . RC similar results when the conjoined names were replaced PN-nom medicine-acc truly with a family name followed by a first name, therefore If the late opening interpretation is chosen, the direct without increasing the number of discourse entities). object (the accusative marked `shinyaku') is to the left These results suggest that a change in the prosodic of the embedded clause boundary, therefore it belongs length of the matrix subject affects the way how readers to the matrix clause together with the matrix subject interpret relative clauses even when the fragments are (`Morishita'). In this case, the matrix verb at the end of not overtly articulated. the sentence must be a predicate that can take the direct This type of completion questionnaire task is com- object as an argument. The dative marked `friends' is monly used in the sentence processing literature to in- also attached to the matrix verb, therefore ditransitive vestigate the types of interpretations that are likely to predicates such as susumeru `recommend' would be a be pursued after a given fragment (see Hirose, 2003, Ex- natural continuation (as in `Morishitai recommended the periments 4 and 5, for reading time data confirming the medicine to the friends that (hei) really trusts'). questionnaire findings). If an early opening interpretation is chosen, the direct One could argue that plausibility factors (how likely is object is part of the relative clause, therefore only the it that `Morishita really trusts his friends' compared to dative-marked NP `friends' has to attach to the matrix `Morishita's friends really trust the medicine'?) or pref- predicate, therefore a verb such as au `meet' is a gram- erences in gap position within the relative clause (gaps matical continuation (as in `Morishita met the friends in subject position are preferred over gaps in object po- that really trust the medicine'). sition in Japanese; e.g., Miyamoto & Nakamura, 2003) Prosodic contours in speech could affect the preference for early opening versus late opening. However, such differences are orthogonal to During oral communication, prosodic contours (such as the subject-length manipulation and are equally likely pauses and word-end lengthening) produced by speakers to affect the interpretations of fragments with a single can help listeners choose between early and late opening name as well as fragments with conjoined names, there- interpretations (Sakamoto, Muraoka & Matsuura, 2005; fore they do not constitute a problem in this case. also Venditti, in press, for a summary of prosodic con- tours in the processing of sentences in Japanese). In sum, although the syntactic ambiguity in (2a, b) Furthermore, Experiment 3 in Hirose (2003) provides remains the same, the prosodic length of the matrix sub- evidence that the length of the matrix subject in frag- ject affects the favored interpretation even when read in ments such as (1) affects the prosodic contours produced silence, thus providing support for the IPH. by speakers. When an accented noun such as `Mor- However, it is conceivable that the number of char- ishita' is used, the subject spans one minor phrase and acters, rather than the prosodic length of the matrix it becomes part of a major phrase together with an ac- subjects, influenced the way the relative clauses were cented noun such as the direct object `medicine' in (3a). interpreted and a number of alternative explanations In contrast, with two accented nouns (e.g., the con- would be possible. For example, at least since the 1970s joined proper names Morishita-to Hosokawa `Morishita (e.g., Frazier & Fodor, 1978) there have been propos- and Hosokawa'), the subject alone constitutes a major als that the perceptual span during reading may affect phrase as shown in (3b). how phrases are associated together. Another possibility The inclusion of the extra accented noun does not is the way working memory may handle longer strings change the nature of the syntactic ambiguity. That is, of letters as they are concatenated into more complex the left edge of the relative clause remains ambiguous chunks, which in turn may define phrasal boundaries. and both alternatives in (2) are still possible when `Mor- If non-phonological aspects of the input strings are ishita' is replaced by `Morishita and Hosokawa'. responsible for the effects reported by Hirose (2003), it Nevertheless, the prosodic markings often accompa- should be possible to replicate them even with partici- nying major phrase boundaries can bias listeners inter- pants who are less likely to be generate implicit prosodic pretations as they are preferentially aligned with the be- contours.