title: The comprehension of sentences with unaccusative verbs in aphasia: a test of the intervener hypothesis.
abstract: BACKGROUND
  It is well accepted that individuals with agrammatic Broca's aphasia have difficulty comprehending some sentences with filler-gap dependencies. While investigations of these difficulties have been conducted with several different sentence types (e.g., object relatives,Wh-questions), we explore sentences containing unaccusative verbs, which arguably have a single noun phrase (NP) that is base-generated in object position but then is displaced to surface subject position. Unaccusative verbs provide an ideal test case for a particular hypothesis about the comprehension disorder-the Intervener Hypothesis-that posits that the difficulty individuals with agrammatic Broca's aphasia have comprehending sentences containing filler-gap dependencies results from similarity-based interference caused by the presence of an intervening NP between the two elements of a syntactic chain.
  
  
  OBJECTIVE
  To assess a particular account of the comprehension deficit in agrammatic Broca's aphasia-the Intervener Hypothesis.
  
  
  METHODS
  We used a sentence-picture matching task to determine if listeners with agrammatic Broca's aphasia (LWBA) and age-matched neurologically unimpaired controls (AMC) have difficulty comprehending unaccusative verbs when placed in subject relative and complement phrase (CP) constructions.
  
  
  RESULTS
  We found above-chance comprehension of both sentence constructions with the AMC participants. In contrast, we found above-chance comprehension of CP sentences containing unaccusative verbs but poor comprehension of subject relative sentences containing unaccusative verbs for the LWBA.
  
  
  CONCLUSIONS
  These results provide support for the Intervener Hypothesis, wherein the presence of an intervening NP between two elements of a filler-gap dependency adversely affects sentence comprehension.
authors.affiliation: SDSU/UCSD Joint Doctoral Program in Language and Communicative Disorders, San Diego, CA, USA.
authors.forename: Natalie
authors.initials: N
authors.lastname: Sullivan
authors.affiliation: School of Speech Language and Hearing Sciences, San Diego State University, San Diego, CA, USA.
authors.forename: Matthew
authors.initials: M
authors.lastname: Walenski
authors.affiliation: SDSU/UCSD Joint Doctoral Program in Language and Communicative Disorders, San Diego, CA, USA; School of Speech Language and Hearing Sciences, San Diego State University, San Diego, CA, USA.
authors.forename: Tracy
authors.initials: T
authors.lastname: Love
authors.affiliation: SDSU/UCSD Joint Doctoral Program in Language and Communicative Disorders, San Diego, CA, USA; School of Speech Language and Hearing Sciences, San Diego State University, San Diego, CA, USA.
authors.forename: Lewis P
authors.initials: LP
authors.lastname: Shapiro
keywords: Aphasia; neurolinguistics; sentence processing; syntax