Michael Walsh Dickey

Real-time comprehension of wh-movement in aphasia : Evidence from eyetracking while listening

Sentences with non-canonical wh- movement are often difficult for individuals with agrammatic Brocas aphasia to understand (, inter alia). However, the explanation of this difficulty remains controversial, and little is known about how individuals with aphasia try to understand such sentences in real time. This study uses an eyetracking while listening paradigm to examine agrammatic aphasic individuals on-line comprehension of movement sentences. Participants eye-movements were monitored while they listened to brief stories and looked at visual displays depicting elements mentioned in the stories. The stories were followed by comprehension probes involving wh- movement. In line with previous results for young normal listeners [Sussman, R. S., & Sedivy, J. C. (2003). The time-course of processing syntactic dependencies: evidence from eye movements. Language and Cognitive Processes, 18, 143-161], the study finds that both older unimpaired control participants (n=8) and aphasic individuals (n=12) showed visual evidence of successful automatic comprehension of wh- questions (like Who did the boy kiss that day at school?). Specifically, both groups fixated on a picture corresponding to the moved element (who, the person kissed in the story) at the position of the verb. Interestingly, aphasic participants showed qualitatively different fixation patterns for trials eliciting correct and incorrect responses. Aphasic individuals looked first to the moved-element picture and then to a competitor following the verb in the incorrect trials. However, they only showed looks to the moved-element picture for the correct trials, parallel to control participants. Furthermore, aphasic individuals fixations during movement sentences were just as fast as control participants fixations. These results are unexpected under slowed-processing accounts of aphasic comprehension deficits, in which the source of failed comprehension should be delayed application of the same processing routines used in successful comprehension. This pattern is also unexpected if aphasic individuals are using qualitatively different strategies than normals to comprehend such sentences, as under impaired-representation accounts of agrammatism. Instead, it suggests that agrammatic aphasic individuals may process wh- questions similarly to unimpaired individuals, but that this process often fails to facilitate off-line comprehension of sentences with wh- movement.

The resolution and recovery of filler-gap dependencies in aphasia: evidence from on-line anomaly detection.

This study examines the on-line processing of sentences with movement using an auditory anomaly detection task (after Borland, Tanenhaus, Garnsey, & Carlson, 1995). Eight agrammatic aphasic participants (four of whom had undergone treatment focused on comprehension and production of filler-gap sentences) and 24 young normal participants listened to sentences and pressed a button when the sentences stopped making sense. Critical sentences contained an anomaly in object relative clauses or conjoined clauses. Results showed that both young normals and aphasic participants were able to reject anomalous sentences of both types. In addition, both groups showed evidence of filler-gap resolution on-line. Importantly, however, there was evidence of a treatment effect for the aphasic patients: those who received treatment showed better performance than those who had not. Treated patients were more successful than the untreated patients in detecting the anomaly in filler-gap conditions, rejecting the anomalous filler-gap sentences reliably more often than the non-anomalous ones, like the young normals. This effect was not noted for untreated participants, i.e., there was no statistical difference between their rejection of anomalous and non-anomalous filler gap sentences. Further, the reaction time data showed that the treated aphasic patients rejections came before sentences end (within 2000 ms), while the majority of responses made by untreated patients did not. These results indicate that individuals with agrammatic aphasia appear to retain some gap-filling capacity and that treatment can improve their ability to make use of this capacity.

The relation between syntactic and morphological recovery in agrammatic aphasia: A case study.

Background: Production of grammatical morphology is typically impaired in agrammatic aphasic individuals, as is their capacity to produce the syntactic structure responsible for licensing that morphology. Whether these two impairments are causally related has been an issue of long‐standing debate. If morphological deficits are a side‐effect of underlying syntactic ones, as has been claimed (Friedmann & Grodzinsky, 1997; Izvorski & Ullman, 1999), therapy that improves the syntactic deficit should remediate the morphological deficit as well. This paper reports a case study of one individual with such co‐occurring impairments and describes their recovery in response to linguistically motivated treatment targeting his syntactic deficits. Methods & Procedures: MD is a 56‐year‐old male diagnosed with non‐fluent Brocas aphasia subsequent to a left‐hemisphere CVA, with limited capacity to produce syntactically complex utterances and grammatical morphology. He was enrolled in therapy using Treatment of Underlying Forms (TUF; Thompson & Shapiro, 2005), targeting production of sentences involving Wh‐movement (object relative clauses). MD participated in twice‐weekly treatment sessions for approximately 2 months, with daily probes assessing his production of treated and untreated sentence types. In addition, probes assessing his grammatical morphology and sentence production were administered pre‐ and post‐treatment. Outcomes & Results: Pre‐treatment scores in tests of grammatical morphology and sentence production indicated deficits in both domains. During treatment, MD successfully acquired production of a variety of sentences with Wh‐movement, although this did not generalise to sentences involving a grammatically distinct movement operation (NP‐movement). Post‐treatment scores also indicated a lack of improvement in production of grammatical morphology. Conclusions: The dissociation between MDs morphological and syntactic recovery indicates that the recovery of syntactic and morphological processes in aphasia may occur independently in some individuals. The result would not be predicted by approaches in which morphological and syntactic impairments are strongly and causally related in aphasia, such as the tree‐pruning hypothesis (Friedmann, 2001; Friedmann & Grodzinsky, 1997). Further, these results reinforce the conclusion that aphasia treatment can lead to generalisation, but only to linguistic material that is in a subset relation to trained structures (Thompson, Shapiro, Kiran, & Sobecks, 2003). This research was supported by the NIH under grant DC‐01948 to C. K. Thompson. The authors are grateful to Audrey Holland and two anonymous reviewers for their exceptionally helpful comments and suggestions. The authors are especially grateful to MD and his family for his participation in this research.

A Psychometric Analysis of Functional Category Production in English Agrammatic Narratives.

Hierarchical models of agrammatism propose that sentence production deficits can be accounted for in terms of clausal syntactic structure [Friedmann, N., & Grodzinsky, Y. (1997). Tense and agreement in agrammatic production: Pruning the syntactic tree. Brain and Language, 56, 397-425; Hagiwara, H. (1995). The breakdown of functional categories and the economy of derivation. Brain and Language, 50, 92-116]. Such theories predict that morpho-syntactic elements associated with higher nodes in the syntactic tree (complementizers and verb inflections) will be more impaired than elements associated with lower structural positions (negation markers and aspectual verb forms). While this hypothesis has been supported by the results of several studies [Benedet, M. J., Christiansen, J. A., & Goodglass, H. (1998). A cross-linguistic study of grammatical morphology in Spanish- and English-speaking agrammatic patients. Cortex, 34, 309-336; Friedmann, N. (2001). Agrammatism and the psychological reality of the syntactic tree. Journal of Psycholinguistic Research, 30, 71-88; Friedmann, N. (2002). Question production in agrammatism: The tree pruning hypothesis. Brain and Language, 80, 160-187], it has also been challenged on several grounds [Burchert, F., Swoboda-Moll, M., & De Bleser, R. (2005a). Tense and agreement dissociations in German agrammatic speakers: Underspecification vs. hierarchy. Brain and Language, 94, 188-199; Lee, M. (2003). Dissociations among functional categories in Korean agrammatism. Brain and Language, 84, 170-188; Lee, J., Milman, L. H., & Thompson, C. K. (2005). Functional category production in agrammatic speech. Brain and Language, 95, 123-124]. In this paper the question of hierarchical structure was re-examined within the framework of Item Response Theory [IRT, Rasch, G. (1980). Probabilistic models for some intelligence and attainment tests (Expanded ed.). Chicago: University of Chicago Press]. IRT is a probabilistic model widely used in the field of psychometrics to model behavioral constructs as numeric variables. In this study we examined production of functional categories (complementizers, verb inflections, negation markers, and aspectual verb forms) in narrative samples elicited from 18 individuals diagnosed with nonfluent aphasia and 18 matched controls. Data from the aphasic participants were entered into an IRT analysis to test (1) whether production of clausal functional categories can be represented as a variable on a numeric scale; and (2) whether production patterns were consistent with hierarchical syntactic structure. Pearson r correlation coefficients were also computed to determine whether there was a relation between functional category production and other indices of language performance. Results indicate that functional category production can be modeled as a numeric variable using IRT. Furthermore, although variability was observed across individuals, consistent patterns were evident when the data were interpreted within a probabilistic framework. Although functional category production was moderately correlated with a second measure of clausal structure (clause length), it was not correlated with more distant language constructs (noun/verb ratio and WAB A.Q.). These results suggest that functional category production is related to some, but not all, measures of agrammatic language performance.

Functional category production in agrammatism: Treatment and generalization effects

Department of Neurology, Northwestern University, USAAccepted 6 July 2006IntroductionThe complexity account of treatment efficacy (CATE; Thompson,Shapiro, Kiran, & Sobecks, 2003) predicts that training complex languagestructures in agrammatism will result in generalize to less complex struc-tures, but only when they share similar derivations. For instance, trainingcomplex sentences derived by ‘wh’ movement, such as object clefts (e.g., Itwas the coach who the skater chased) results in generalization to less com-plex ‘wh’ movement structures such as object-extracted wh questions (Whodid the skater chase?), but not to ‘NP’ movement structures (e.g. passivevoice: The coach was chased by the skater). To date, CATE has been testedwith noncanonical sentence structures, which are particularly difficult foragrammatic speakers. In this paper, we examined the generalization pat-terns that result from training functional morphology in basic canonicalsentences. Specifically, we examined patterns of acquisition and general-ization of:(1) Complementizers: They wonder if the cat is following the mouse.(2) Past tense inflections: Yesterday the cat followed the mouse.(3) Presentagreement inflections: Nowadaysthe cat follows the mouse.While all three morphemes are considered functional category mem-bers, complementizers and tense/agreement are not equivalent with respectto their structural position in the syntactic tree. Complementizers are ele-ments generated in the complementizer phrase (CP); while tense and agree-ment inflections are both elements licensed by the inflection phrase (IP).Therefore, based on CATE, we predicted generalization between tense(2) and agreement (3), but NOT between complementizers (1) and tense(2) or between complementizers (1) and agreement (3), since they arelicensed by distinct functional projections.In contrast to CATE,the Tree pruninghypothesis (TPH; FriedmannG Thompson, 2005), and spontaneouslanguage patterns. Participants were between 36–68 years old, and hadbetween 12–20 years of education.Design and analysisA single subject multiple baseline design across behaviors and partici-pants was used. Pre- and post-testing measures included the Westernaphasia battery (WAB; Kertesz, 1982), the Verb Inflection Test (VIT;Bastiaanse & Thompson, 2005), and two neuroimaging (fMRI) tasksdesigned to examine neural patterns associated with production and com-prehension of the target morphemes. Baseline probes were also adminis-tered to assess production of all target morpheme using picture stimuli(line drawings).During each treatment session participants were asked to produce 15sentences containing the target morpheme. Three types of sentences weretrained: those with complementizers (1), past tense (2), and present tense(3). Training included: (a) thematic role training, (b) placement of writtensentence constituent cards in their surface structure position, (c) readingtarget sentences, (d) reassembly of scrambled written sentence constituentcards, and (d) re-reading sentences. Prior to each session probes, identicalto baseline, were administered to evaluate learning and generalizationpatterns.doi:10.1016/j.bandl.2006.06.049

Verb argument structure encoding during sentence production in agrammatic aphasic speakers: An eye-tracking study

a Aphasia and Neurolinguistics Research Laboratory, Department of Communication Sciences and Disorders, Northwestern University, 2240 Campus Dr. Evanston, IL 60208, USA b Department of Neurology, Northwestern University, Evanston, IL 60208, USA c Cognitive Neurology and Alzheimer’s Disease Center, Northwestern University, Evanston, IL 60208, USA d Department of Psychology, Georgia Institute of Technology, Atlanta, GA 30332, USA

Perception of functional morphology in agrammatic Broca's aphasia

Individuals with agrammatic Broca’s aphasia show marked deficits in production of functional morphemes such as complementizers (like that and if) and tense and agreement markers (like –ed and –s). Furthermore, production of complementizers appears to be more impaired in many aphasic individuals than production of verbal morphology (Friedmann Hagiwara, 1995; & Grodzinky, 1997; Milman, Dickey, & Thompson, 2004). Some accounts, in particular the Tree-Pruning Hypothesis (Friedmann & Grodzinky, 1997), have linked this production deficit to the hierarchical syntactic structure associated with these morphemes. Specifically, morphemes associated with higher functional projections (e.g., complementizers) are more impaired than those associated with lower projections (e.g., verbal inflections). This paper presents the results of two grammaticality judgment experiments examining the perception of complementizers and verb inflections by English speakers with Broca’s aphasia. If perception patterns with production, perception of complementizers is expected to be more impaired than perception of verbal morphology, particularly under the Tree-Pruning Hypothesis.

Impairments of derivational word formation in agrammatic aphasia

Agrammatic aphasic production disorders are often considered syntactic in nature; for example, several theories of agrammatic production point to a mis-structured Inflectional Phrase (e.g., Friedmann & Grodzinsky, 1997; Grodzinsky, 1990; Wenzlaff & Clahsen, 2005) as the locus of the impairment. If agrammatic aphasia reflects this sort of syntactic deficit, production of inflectional morphology should be compromised, while derivational morphology should be intact. We tested agrammatic production of real derived forms and novel (pseudoword) derived forms. While production of real derived forms may involve whole-word lexical access rather than affixation, production of derived pseudowords by necessity involves word-formation rules.

Conclusions and Remaining Questions

This book has examined some issues in the processing of tense, the process by which the human language processor assigns an interpretation to past-tense morphology. It began with a set of questions regarding the nature of the processor’s operations in such interpretation. These questions are repeated in (1a-d) below.

Sequence of Tense and Simplicity

As discussed in Chapter 1, the past tense morphology of an embedded clause can have two different interpretations, as illustrated in (1) below.