Brain and Language 103 (2007) 8–249 www.elsevier.com/locate/b&l
Verb argument structure encoding during sentence production in agrammatic aphasic speakers: An eye-tracking study Cynthia K. Thompson a,b,c,*, Michael Walsh Dickey a, Soojin Cho a, Jiyeon Lee a, Zenzi Griffin d 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
Introduction Verb and sentence production deficits are characteristic of agrammatic aphasia and have been attributed, at least in part, to verb argument structure (e.g., Kiss, 2000; Miceli, Silveri, Villa, & Caramazza, 1984, and many others). Verbs with a greater number of arguments, such as three-argument verbs (as in 1 below) are more challenging to produce than verbs with fewer, i.e., two-argument verbs (as in 2) for individuals with agrammatic aphasia, with this effect shown in agrammatic speakers across languages (English: Kim & Thompson, 2000, 2004; Italian: Luzzatti et al., 2002; German: De Bleser & Kauchke, 2003). Notably, however, these observations have derived from off-line production studies; thus, little is known about what goes awry in agrammatic sentence production. The purpose of this study was to investigate this question using eye-tracking methodology, which records eye-movements as sentences are generated. Specifically, we enquired whether grammatical encoding proceeds normally in agrammatic production. (1) The boy is giving the guitar to the musician (2) The dog is chasing the cat
A total of 35 line-drawings of action pictures (20 for two-argument verbs) were used to elicit target sentences. Two- and three-argument verbs were roughly matched for log lemma frequency (1.561 vs. 2.099) in CELEX. Pictures were presented on a computer monitor and participants were asked to describe them using a single sentence. In order to avoid word retrieval difficulties, aphasic participants were familiarized with all nouns and verbs used in the pictures prior to the experiment. Participants’ eye-movements were recorded by an ASL 6000 series remote eye-racker, and their speech was recorded by SoundEdit 16. Following the experiment, production accuracy, speech onset latency, and eye-movement patterns were measured. Results
(Two-argument verb)
Participants Twelve monolingual speakers of English (age: 18–27) served as young normal controls. Six individuals with agrammatic Broca’s aphasia, assessed by the Western Aphasia Battery (Kertesz, 1982, AQ: 66.8– 86.4), narrative language analysis, and other testing participated in the
Corresponding author. Fax: +1 847 467 7377. E-mail address:
[email protected] (C.K. Thompson).
doi:10.1016/j.bandl.2007.07.012
Stimuli and procedures
(Three-argument verb)
Methods
*
study (age: 38–58, post-onset: 1–16 years, resulting from a thromboembolic stroke in the left hemisphere). The aphasic participants were native speakers of English; all but one were premorbidly right-handed; and all demonstrated good visual and hearing acuity.
Aphasic participants, as expected, showed overall patterns of longer speech onset latency and reduced accuracy in their sentence production attempts, as compared to normal control participants. In addition, while three-argument verbs elicited longer speech onset latency than two-argument verbs for control participants (p < .05), the agrammatic patients showed no significant difference between latencies for production of the two sentence types (F(1, 205) = 3.607, p = .059). Control participants showed incremental patterns of eye-movements, with gazes to the pictured agent dominating pre-speech eye-movements (p < .05, t-test). Furthermore, eye-movements after speech onset showed evidence of incremental planning and encoding, as shown in previous studies (Griffin & Bock, 2000) (see Fig. 1). Following initial looks to the Agent, participants looked at the Theme (followed by Goal for three-argument sentences) in the order in which they were produced, with fixations preceding production of each. Interestingly, aphasic participants showed similar
Abstract / Brain and Language 103 (2007) 8–249
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Fig. 1. Mean gaze duration by speech regions for control and aphasic participants during sentence production. (a) Two- (left) and three- (right) argument verb conditions for normal control participants (b) Correct responses in two- (left) and three- (right) argument verb conditions for aphasic participants (c) Incorrect responses in two- (left) and three- (right) argument verb conditions for aphasic participants incremental patterns for two-argument verbs (p < .05, t-test) but not for three-argument verbs, and only for correct responses. For incorrect responses, aphasic participants did not show patterns of incrementality.
demands. These findings replicate and extend data supporting the argument structure complexity hypothesis (Thompson, 2003). References
Discussion The eye-movement data from individuals with agrammatic aphasia showed that both sentence planning and production patterns are qualitatively different than that of normal participants, indicating that both grammatical encoding and production difficulty influence their erroneous sentence production. However, an argument structure complexity effect was found in both off-line (production accuracy) and on-line (speech onset latencies) data for control and aphasic participants, indicating that verbs with greater argument structure complexity engender greater encoding
De Bleser, R., & Kauchke, C. (2003). Acquisition and loss of nouns and verbs: Parallel or divergent patterns? Journal of Neurolinguistics, 16(2–3), 213–229. Griffin, Z., & Bock, K. (2000). What the eyes say about speaking. Psychological Science, 11, 274–279. Kertesz, A. (1982). Western aphasia battery. New York: Grune Stratton. Kim, M., & Thompson, C. K. (2000). Patterns of comprehension and production of nouns and verbs in agrammatism: Implications for lexical organization. Brain and Language, 74(1), 1–25.
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Abstract / Brain and Language 103 (2007) 8–249
Kim, M., & Thompson, C. K. (2004). Verb deficits in Alzheimer’s disease and agrammatism: Implications for lexical organization. Brain and Language, 88, 1–20. Kiss, K. (2000). Effects of verb complexity on agrammatic aphasics’ sentence production. In R. Bastiaanse & Y. Grodzinsky (Eds.), Grammatical disorders in aphasia (pp. 123–151). London: Whurr. Luzzatti, C., Raggi, R., Zonca, G., Pistarini, C., Contardi, A., & Pinna, G-D. (2002). Verb-noun double dissociation in aphasic lexical
impairments: The role of word frequency and imageability. Brain and Language, 81(1–3), 432–444. Miceli, G., Silveri, M. C., Villa, G., & Caramazza, A. (1984). On the basis for the agrammatic’s difficulty in producing main verbs. Cortex, 20, 207–220. Thompson, C. K. (2003). Unaccusative verb production in agrammatic aphasia: the argument structure complexity hypothesis. Journal of Neurolinguistics, 16, 151–167.
