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Why do children struggle with subject-experiencer verbs? A neurobiological investigation
Poster Session D, Saturday, September 13, 5:00 - 6:30 pm, Field House
Sahil Luthra1, William Snyder2, Nabin Koirala2,3,4, Roeland Hancock3; 1Carnegie Mellon University, 2University of Connecticut, 3Yale University, 4Nathan Kline Institute for Psychiatric Research
Introduction: Until the age of about five-and-a-half, children acquiring English have difficulty processing passive-voice sentences with subject-experiencer (SE) verbs (e.g., “hate,” “remember,” “love,” “see”), as in “Sharks are feared by Mary.” We suggest this delay is a product of neurodevelopment, such that the timing of changes in a child’s grammatical capacities can be related to developmental changes in the child’s brain. We further propose that passivizing an SE verb requires a “semantic coercion” operation on the verb’s meaning and hypothesize that this operation is supported by some region outside canonical language areas that is associated with ongoing maturational change between ages five and six. Linguistic Analysis: Arad (1998) argues that the default conceptualization of an SE verb can be described with a spatial contact metaphor. In our example, the experiencer MARY is “located with” a mental object FEAR, and the target of that FEAR is SHARKS. Landau (2010) argues that locative arguments are normally VP-internal; if so, this yields a syntactic structure where the experiencer is projected as a VP-internal argument. Verbs can only be passivized if they project a VP-external argument (Baker et al., 1989), meaning the default conceptualization of the SE verb blocks passivization. We suggest that one can passivize an SE verb by applying semantic coercion to obtain a more sophisticated conceptualization of the verb’s meaning, acknowledging that the mental object (FEAR) is actually something that the experiencer (MARY) possesses. The resultant syntactic derivation projects a VP-external argument (i.e., the possessor; Kratzer 1996), allowing for passivization. Methods: We tested our hypothesis using an fMRI study with English-speaking adults (N=32). Participants performed a fixed-pace reading task wherein they encountered sentences varying in both voice (active / passive) and verb type (SE / actional) as well as anomalous sentences. Comprehension questions followed 50% of trials. Participants also completed functional localizer tasks to identify the language and multiple demand networks (Fedorenko et al., 2011). Results: Behaviorally, participants exhibited worse comprehension of passive sentences than active ones and worse comprehension of sentences with SE verbs versus those with actional verbs. Crucially, we found that the online processing of SE passives compared to actional passives was linked to increased activation in a relatively late-maturing region of the brain: ventromedial prefrontal cortex (vmPFC). This same region emerged in a contrast of SE passives > anomalous sentences; thus, our effect was not driven by semantic violations per se. No voice x verb type interactions were observed in regions identified by the localizer tasks, indicating that the neural correlates of SE passive processing lie outside both canonical language regions and multiple demand regions. Discussion: Notably, vmPFC has been implicated in other forms of semantic coercion (e.g., Pylkkänen, 2008) and is still undergoing structural maturation between the ages 5 and 6. Thus, our findings are consistent with the proposal that comprehending SE passives involves semantic coercion of the verb’s meaning. To our knowledge, this is the first study to find a “signature” of children's developmental stages in adults’ functional localization for language.
Topic Areas: Syntax and Combinatorial Semantics, Language Development/Acquisition