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Aphasiology Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/paph20
Pronoun processing in Broca’s aphasia: Discourse–syntax effects in ambiguous anaphora resolution a
E. Peristeri & I. M. Tsimpli
a
a
School of English, Department of Theoretical and Applied Linguistics, Aristotle University of Thessaloniki, Thessaloniki, Greece Published online: 25 Aug 2013.
To cite this article: E. Peristeri & I. M. Tsimpli (2013) Pronoun processing in Broca’s aphasia: Discourse–syntax effects in ambiguous anaphora resolution, Aphasiology, 27:11, 1381-1407, DOI: 10.1080/02687038.2013.828344 To link to this article: http://dx.doi.org/10.1080/02687038.2013.828344
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Aphasiology, 2013 Vol. 27, No. 11, 1381–1407, http://dx.doi.org/10.1080/02687038.2013.828344
Pronoun processing in Broca’s aphasia: Discourse–syntax effects in ambiguous anaphora resolution
Downloaded by [Aristotle University of Thessaloniki] at 03:47 20 July 2015
E. Peristeri and I. M. Tsimpli School of English, Department of Theoretical and Applied Linguistics, Aristotle University of Thessaloniki, Thessaloniki, Greece
Background: The interpretation of ambiguous subject pronouns in a null subject language, like Greek, requires that one possesses grammatical knowledge of the two subject pronominal forms, i.e., null and overt, and that discourse constraints regulating the distribution of the two pronouns in context are respected. Aims: We investigated whether the topic-shift feature encoded in overt subject pronouns would exert similar interpretive effects in a group of seven participants with Broca’s aphasia and a group of language-unimpaired adults during online processing of null and overt subject pronouns in referentially ambiguous contexts. Method & Procedures: An offline picture–sentence matching task was initially administered to investigate whether the participants with Broca’s aphasia had access to the gender and number features of clitic pronouns. An online self-paced listening picture-verification task was subsequently administered to examine how the aphasic individuals resolve pronoun ambiguities in contexts with either null or overt subject pronouns and how their performance compares to that of language-unimpaired adults. Outcomes & Results: Results demonstrate that the Broca group, along with controls, had intact access to the morphosyntactic features of clitic pronouns. However, the aphasic individuals showed decreased preference for non-salient antecedents in object position during the online resolution of ambiguous overt subject pronouns and preferred to pick the subject antecedent instead. Conclusions: Broca’s aphasic participants’ parsing decisions in the online task reflect their difficulty with establishing topic-shifted interpretations of the ambiguous overt subject pronouns. The presence of a local topic-shift effect in the immediate temporal vicinity of the overt pronoun suggests that sensitivity to the marked informational status of overt pronouns is preserved in the aphasic individuals, yet, it is blocked under conditions of global sentential processing. Keywords: Broca’s aphasia; Ambiguous pronouns; Syntax–discourse interface.
Address correspondence to: E. Peristeri, School of English, Department of Theoretical and Applied Linguistics, Aristotle University of Thessaloniki 54124, Thessaloniki, Greece. E-mail:
[email protected] We would like to thank all the individuals with Broca’s aphasia who participated in this study, as well as their relatives for their precious help. We are also grateful to the neurologists Dr. Tasos Papapostolou and Dr. Katerina Anyfadi for their help with the Broca individuals’ neurological diagnosis. The authors report no declarations of interest and no sources of financial support for this study. Part of the data sets used in this article is derived from Eleni Peristeri’s unpublished Ph.D. thesis (2010) “Exploring the Discourse– Syntax and the Lexicon-Syntax Interfaces in Language Pathology: Evidence from Broca’s Aphasia”, School of English, Department of Theoretical and Applied Linguistics, Aristotle University of Thessaloniki, Thessaloniki, Greece, which was supported in part by scholarships from the Propondis Private Foundation and the Research Committee of the Aristotle University of Thessaloniki, Thessaloniki, Greece. © 2013 Taylor & Francis
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Anaphoric reference has been used in a number of language processing experiments in Broca’s aphasia as a means to illuminate operations underlying normal comprehension and how these go awry in aphasia (Baauw, Ruigendijk, Cuetos, & Avrutin, 2011; Burkhardt, Avrutin, Piñango, & Ruigendijk, 2008; Choy & Thompson, 2010; Edwards & Varlokosta, 2007; Edwards, Varlokosta, & Payne, 2003; Friederici, Weissenborn, & Kail, 1991; Gavarró, 2008; Grodzinsky, Wexler, Chien, Marakovitz, & Solomon, 1993; Jarema & Friederici, 1994; Love, Nicol, Swinney, Hickok, & Zurif, 1998; Nerantzini, 2012; Nerantzini, Papadopoulou, & Varlokosta, 2010, 2011; Piñango & Burkhart, 2001, 2005; Ruigendijk, Vasi´c, & Avrutin, 2006; Thompson & Choy, 2009; Varlokosta & Edwards, 2003; Vasi´c, Avrutin, & Ruigendijk, 2006, among others). The nature of both online and offline processing of pronouns within the framework of Chomsky’s Binding Theory (1981) has been explored in individuals with a lesion in Broca’s area, especially since the specific area has been claimed to be crucially involved in controlling for the semantic and morphosyntactic well-formedness of Chomsky’s binding constraints. Previous studies on the processing of referential dependency relations have proposed the form-specific multiple-constraint approach which maintains that anaphor resolution is guided by multiple factors weighted differently for each anaphoric form (e.g., Kaiser, 2003; Reuland, 2001). More specifically, Reuland’s (2001) economybased model sets forth the following hierarchy of levels at which reference can be established: Syntax .10). Post-hoc comparisons with the Bonferroni test for the null pronoun trials showed that the Broca group provided more matches for the subject relative to the object (p =.000; such performance was exhibited by 6/7 aphasic participants: p =.005 (P2), p =.015 (P3), p =.037 (P4), p =.001 (P5), p =.037 (P6) and p =.058 (P7) and the other referent (p =.000; such performance was exhibited by all the aphasic participants: p =.000, p =.000, p =.000, p =.001, p =.015, p =.001 and p =.037), and more matches for the object relative to the other referent (p =.005; such performance was exhibited by 5/7 aphasic participants: p =.037 (P1), p =.037 (P3), p =.005 (P4), p =.001 (P6) and p =.05 (P7); on the other hand, the aphasic participants provided significantly more matches for the subject and the object as opposed to the other referent for the overt pronoun trials (p =.000; such performance was exhibited by all the aphasic participants: p =.005, p =.001, p =.037, p =.05, p =.005, p =.05 and p =.005 for the subject vs. other dissociation, and p =.005,
TABLE 3 Language-unimpaired adults’ and Broca participants’ mean RTs (in msecs) (and SDs) for the null and the overt pronoun trials in the self-paced listening sentence picture-verification task Null pronoun trials
Overt pronoun trials
Group
Subject
Object
Other
Subject
Object
Other
Controls
1416.5 (793.5) 7721.3 (3185.4)
1785.9 (1283.0) 10363.9 (5360.1)
1406.0 (792.0) 11012.3 (4372.9)
1734.0 (1098.0) 6231.9 (3032.3)
1348.5 (706.7) 6962.3 (2832.0)
1542.0 (796.1) 8380.0 (2599.8)
Broca participants
ANAPHORA IN BROCA’S APHASIA
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p =.001, p =.001, p =.05, p =.001, p =.037 and p =.037 for the object vs. other dissociation), while no significant dissociation was found between the aphasic group’s subject and object matching rates. Independent samples t-tests comparing the controls with the aphasic group’s matching rates for each pronoun-type (null, overt) revealed that the controls tended to provide significantly more matches than the Broca participants in the object (t (30) = 3.021, p =.005) and the other referent condition (t (30) = 1.980, p =.05) for the overt pronoun trials only; on the other hand, the Broca group tended to provide marginally significantly more matches than the control group in the overt pronoun-subject co-reference condition (t (30) = 1.903, p =.06).
RTs on matching decisions Table 3 presents the RTs and SDs per group and referent-type for both the null and the overt pronoun trials. Between-group comparisons on RTs were avoided since aphasic participants’ use of their non-dominant hand as well as the inter-individual variability evident in the aphasic individuals’ high SDs constitute confounds that represent a threat in neuropsychological investigation. As such, we only conducted separate repeated measures ANOVAs for each group with pronoun and referent-type as within-subjects factors. For the controls, no significant main effects or interactions were observed. For the Broca group, there was a main effect of pronoun (F (1, 12) = 12.648, p
