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Abstract
While there is ample evidence that prosody and syntax mutually constrain each other, there is considerable uncertainty about the nature of this interface. Here, we explore this issue with prepositional phrase attachment ambiguities (You can feelA the catB with the feather). Prior research has been motivated by two hypotheses: (1) the absolute boundary hypothesis (ABH) posits that attachment preferences depend on the size of the prosodic boundary before the ambiguous phrase (boundary B) and (2) the relative boundary hypothesis (RBH) links attachment to the relative size of boundary B and any boundary between the high and low attachment site (boundary A). However, few experiments test the unique predictions of either theory. Study 1 examines how syntax influences prosodic production. The results provide modest support for RBH and stronger support for ABH. In Study 2, we systematically vary the size of both boundaries in an offline comprehension task. We find that absolute boundary strength influences interpretation when relative boundary strength is held constant, and relative boundary strength influences interpretation when absolute boundary strength is held constant. Thus, our theory of the prosody–syntax interface must account for effects of both kinds.
Acknowledgements
We are grateful to Jennifer Venditti, who conducted the ToBI analyses on the utterances from Snedeker and Trueswell (2003), and to Amanda Worek, who kept the lab running smoothly. A special thanks to Stefanie Shattuck-Hufnagel for introducing the authors. This material is based upon work supported by the National Science Foundation (0623845).
Notes
1These comprised 16% of the tokens in Experiment 1 in which speakers were aware of the ambiguity and 4% of the tokens in Experiment 2 in which they were unaware. All the ambiguous boundaries occurred before the prepositional phrase. In Experiment 1, the proportion of these utterances appearing in high-attachment contexts was intermediate between utterances with a 0 boundary in this location and those with an ip boundary there, suggesting that they were truly ambiguous. In Experiment 2, they were too infrequent to characterise.
2We used only eight items for two reasons. First, Snedeker and Trueswell (2004) normed potential instruments for only eight equi-biased verbs and we wished to make use of these norms. Second, the present study served as an offline validation study for a visual-world experiment which employed an act out task to test young children, thus placing additional constraints on the verbs that could be used. Each participant heard the same base sentence in four different prosodies, thus the number of critical items was 32 per participant.
3While the only way to semantically interpret the low attachment is as a modifier, the high attachment of a phrase can have several semantic interpretations (accompaniment, location, instrument, etc.). For these particular verbs and prepositional objects, the instrument interpretation was dominant, as evidenced by participants’ responses in an act out task (Snedeker & Trueswell, Citation2004).
4There are two opposing predictions that might be made about the effects of word length on the interpretation of these utterances. First, on a theory in which listeners evaluate prosodic boundaries according to their informativeness (e.g., Clifton et al., 2002), the use of a longer direct-object noun should make the boundary after it less informative. This would result in more low attachments in the conditions with ip or IP breaks before the prepositional phrase. Second, if we entertain the hypothesis that attachment decisions depend in part on the activation of constituents and that the activation rapidly dissipates (Altmann, Citation1998), then we might expect that redundant material between the onset of the noun and the ambiguous phrase to decrease the number of low attachments. Thus, the lack of any effect could reflect the opposing effects of these two processes. Or it could suggest that the length manipulation was too weak to exert any effect at all. Across the eight conditions, the long nouns were only 166 ms longer than the short nouns.
5In addition, there was a small but reliable interaction between Prosody Strength and Order, F1(2, 48) = 3.19, p=.05; F2(2, 14) = 8.92, p=.005. There were no other reliable effects or interactions. Critically, there was no reliable effect of number of syllables in the direct-object noun, F1(1, 48) = 1.12, p>.2; F2(1, 7) = 4.22, p=.08, suggesting that our length manipulation did not have a strong influence on interpretation of the ambiguous phrase.
6Where possible, these hypotheses were tested in within-subjects comparisons. However, for some hypotheses between-subjects comparisons were necessary (italics in ). This raises the concern that differences between individual cells could reflect the mix of structures in the two lists rather than differences in the particular cells under consideration. To explore this, we conducted one-way ANOVA's to find out whether the interpretation of the neutral no break (0,0) and the neutral ip break (ip, ip) utterances varied across the three Prosody Strength conditions. We found no evidence that they did (all Fs < 1, all ps>.5).
7This is clearly inspired by Schafer and colleagues’ Focus Attraction Hypothesis (Schafer et al., 1996), though they cannot be blamed for our particular implementation.
8Full development of 2ABH would have to specify how the relevant location A is defined. The ABH (as we defined it) grants no role to an earlier boundary. RBH proposals typically argue that multiple boundaries between the high-attachment site and the low-attachment site may be relevant (see e.g., Schafer et al., 2000). In the short simple sentences used in the present study, we can bypass this issue, since there are no likely break locations between position A and B.
