Unaccusativity in Sentence Production

Linguistic analyses suggest that there are two types of intransitive verbs: unaccusatives, whose sole argument is a patient or theme (e.g., fall), and unergatives, whose sole argument is an agent (e.g., jump).¹ Past psycholinguistic experiments suggest that this distinction affects how sentences are processed: for example, it modulates both comprehension processes (Bever and Sanz 1997, Friedmann et al. 2008) and production processes (Kegl 1995, Kim 2006, M. Lee and Thompson 2004, J. Lee and Thompson 2011, McAllister et al. 2009). Given this body of evidence, it is reasonable to assume, as we do here, that this distinction is directly relevant to psycholinguistic theorizing. However, especially in production, exactly how this distinction affects processing is unknown, beyond the suggestion that unaccusatives somehow involve more complex processing than unergatives (see M. Lee and Thompson 2011). Here we examine how real-time planning processes in production differ for unaccusatives and unergatives. We build on previous studies on lookahead effects in sentence planning that show that verbs are planned before a deep object is uttered but not before a deep subject is uttered (Momma, Slevc, and Phillips 2015, 2016). (We use terms like deep subject in a theory-neutral fashion, with no intended commitment to a specific syntactic encoding.) This line of research sheds light on the broader issue of how the theory of argument structure relates to sentence production.

1 Unaccusativity and the Timing of Verb Planning in Sentence Production

The Unaccusative Hypothesis claims that the subject of an unaccusative verb originates as the object of the verb (e.g., Burzio 1986, Perlmutter 1978). Supporting this hypothesis, a range of linguistic phenomena, including ne-cliticization and auxiliary selection in Italian (Burzio 1986), English resultatives (Levin and Rappaport Hovav 1995), and possessor datives in Hebrew (Borer and Grodzinsky 1986), suggest that the subjects of unaccusative verbs behave like objects. Reflecting this object-like nature of unaccusative subjects, in transformational theories such as Government-Binding Theory (Chomsky 1981) unaccusative subjects are considered to be base-generated in the object position and moved to the subject position (e.g., Burzio 1986).

Recent studies on the time course of sentence planning suggest that speakers plan verbs (specifically, verbs' lemma representations; Kempen and Huijbers 1983; see Levelt, Roelofs, and Meyer 1999 for a detailed review) before they articulate a deep object, but not before they articulate a deep subject.² These studies support an intermediate position between production models that assume that verbs must be planned before all arguments (e.g., Bock and Levelt 1994) and models that assume that no advance verb planning is needed (e.g., Schriefers, Teruel, and Meinshausen 1998). Specifically, we have shown (Momma, Slevc, and Phillips 2016) that verbs are planned before the object noun is uttered but not before the subject noun is uttered in Japanese active sentences. Similarly, we have shown that verbs are planned before subject nouns are uttered in passive but not in active sentences in English (Momma, Slevc, and Phillips 2015). These studies together suggest that verbs are planned before a deep object, regardless of case marking/grammatical function or whether a noncanonical word order is involved. This finding makes an interesting prediction about the production of intransitive sentences. If unaccusative subjects are deep objects, unlike unergative subjects, then unaccusative sentences but not unergative sentences should require advance planning of the verb before the subject noun is articulated. If this prediction is correct, it would show that the subject of unaccusative sentences is processed like a deep object in sentence production, and that split intransitivity directly affects the time course of speaking.

One way to study the timing of verb planning in sentence production is to use the extended picture-word interference paradigm (Meyer 1996, Momma, Slevc, and Phillips 2015, 2016, Schriefers, Teruel, and Meinshausen 1998). In an extended picture-word interference experiment on verb planning, participants describe pictures depicting an action/event in sentential form. At the same time as they see each picture, or slightly before/after, they also see or hear a distractor word. This distractor word is sometimes semantically related to the target...