Is it all relative? Effects of prosodic boundaries on the comprehension and production of attachment ambiguities

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). 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.