Placing a prosodic boundary before a phrase may influence its syntactic analysis. However, the boundary's effect depends on the presence, size, and position of other, earlier, prosodic boundaries. In three experiments, we extend previous results about the effect of the position of the early boundary. In sentences in which a final phrase may modify either a local verb or an earlier verb, a boundary immediately after the first verb leads to more first-verb attachments than when the earlier boundary appears in another position between the two verbs (Experiments 1 and 2). This effect cannot be attributed to weaker effects of more distant boundaries (Experiment 2), but is likely due to the first verb being more prominent when a boundary immediately follows it, since similar effects are observed when the verb is accented (Experiment 3). The results support the informative boundary hypothesis and show that the impact of earlier, nonlocal boundaries is not fully uniform.
There has been considerable interest in the question of how intonation-in particular, prosodic boundaries- influences the processing of a sentence (e.g., Beach, 1991; Kjelgaard & Speer, 1999; Kraljic & Brennan, 2005; Lehiste, 1973; Nespor & Vogel, 1986; Price, Ostendorf, Shattuck-Hufnagel, & Fong, 1991; Pynte & Prieur, 1996; Schafer, Speer, Warren, & White, 2000). The vast majority of researchers have examined sentences in which the presence or location of a single prosodic boundary affects the division of a sentence into syntactic phrases or affects the attachment of one phrase to others.
In our previous work, we investigated the effect of multiple prosodic boundaries, which led to the informative boundary hypothesis (Carlson, Clifton, & Frazier, 2001; Clifton, Carlson, & Frazier, 2002; cf. Schafer, 1997, for a position similar in some respects to ours). This hypothesis is that listeners interpret a prosodic boundary before a constituent that could be attached to either of two earlier constituents with reference to the presence and size of any relevant earlier boundary. For example, in Example 1 after John visited can be attached to the phrase headed by learned, where it modifies learned as in the paraphrase in Example 1a, or it can be attached to telephoned, for the meaning in Example 1b.
(1) Susie learned that Bill telephoned after John visited.
a. Susie learned (after John visited) that Bill telephoned.
b. Susie learned something-namely, that Bill telephoned after John visited.
If there are no relevant earlier boundaries, a boundary before the ambiguously attached constituent discourages local (low) attachment (see, e.g., Price et al., 1991). That is, a prosodic boundary immediately preceding after John visited may favor attachment to the high attachment site learned rather than to the low attachment site telephoned. But, according to the informative boundary hypothesis, if a (relevant) earlier prosodic boundary is larger than the boundary after telephoned, the prosody may still favor local attachment of after John visited to telephoned, even though a prosodic boundary intervenes. The informative boundary hypothesis takes a relevant earlier boundary to be a boundary that intervenes between the possible low and high attachment sites.
To specify the size of a boundary, we assume a phonological system that distinguishes word boundaries, intermediate phrase (ip) boundaries, and intonational phrase (IPh) boundaries. An IPh is the largest unit, and it contains one or more ips. An ip must contain one or more words and at least one accented constituent. These prosodic units (as well as prosodic words) are identified following the ToBI system, a prosodic annotation procedure inspired by Pierrehumbert (1980) and explained in Beckman and Elam (1997). The ends of both types of prosodic phrases (IPhs and ips) are associated with tonal changes, increased duration, and optional pausing, with IPhs involving more extreme changes. …