Time reference decoupled from tense in agrammatic and fluent aphasia

Abstract

Background: Reference to an event’s time frame can be accomplished through verb inflection. In agrammatic aphasia, a deficit in past time reference has been identified by Bastiaanse and colleagues (2011). In fluent aphasia, specific problems with this time frame (expressed by the past tense) have been found as well (Dragoy & Bastiaanse, 2013; Jonkers & de Bruin, 2009). However, time reference does not always coincide with tense; in languages such as Dutch and English, reference to the past can be established by using past tense (e.g., “he wrote a letter”) or a present tense auxiliary in combination with a participle, i.e., the present perfect (e.g., “he has written a letter”).

Aims: The goal of this study is twofold. First, it aims to untangle tense problems from problems with past time reference through verb morphology in people with aphasia. Second, this study aims to compare the production of time reference inflection by people with agrammatic and fluent aphasia.

Methods & Procedures: A sentence completion task was used to elicit reference to the non-past and past in Dutch. Reference to the past was tested through (1) a simple verb in past tense and (2) a verb complex with an auxiliary in present tense + participle (the present perfect). Reference to the non-past was tested through a simple verb in present tense. Fourteen agrammatic aphasic speakers, sixteen fluent aphasic speakers, and twenty non-brain-damaged speakers (NBDs) took part in this study. Data were analysed quantitatively and qualitatively.

Outcomes & Results: NBDs scored at ceiling and significantly higher than the aphasic participants. Agrammatic speakers performed worse than fluent speakers, but the pattern of performance in both aphasic groups was similar. Reference to the past through past tense and [present tense auxiliary + participle] was more impaired than reference to the non-past. An error analysis revealed differences between the two groups.

Conclusions: People with agrammatic and fluent aphasia experience problems with expressing reference to the past through verb inflection. This past time reference deficit is irrespective of the tense employed. The error patterns between the two groups reveal different underlying problems.

Keywords:

• Agrammatic aphasia
• Fluent aphasia
• Time reference
• Tense

We would like to thank all the participants of this study. Not to forget, we also want to thank Peter Mariën, all the speech therapists, clinical linguists, and other people that brought us in contact with the participants and provided testing space. We thank Felix Golcher for his extensive advice in statistical analyses and Gosse Bouma for his frequency analyses. We want to express our sincere gratitude to Katrina Gaffney and two anonymous reviewers for their insightful and valuable comments on two earlier versions of the article. Laura S. Bos was supported by a short-term grant of the German Research Foundation (DFG) as part of the Collaborative Research Center SFB 632 “Information Structure.”

Notes

¹ The meaning of the Dutch present perfect is closer to the English simple past than to the English present perfect, but to indicate that it is a periphrastic verb form, the literal translation (e.g., “has written”) will be used throughout this article. In Dutch, the present perfect is commonly used to refer to the past, unlike in English. Still, the simple past of lexical verbs appears around twice as often as the present perfect in the Spoken Dutch Corpus (2009).

² This paragraph is only on regular verbs, since the distinction between regular and irregular verbs is outside the scope of this article.

³ Aronson (1977), Partee (1973), and Zagona (2013) suggested that future tense should be seen as a sub-class of present tense, because it is derived from the present tense via modal and aspectual features. This view is adopted here by distinguishing between past and non-past time reference.

⁴ In their article, Nanousi et al. (2006) use the term “simple future” for periphrastic future.

⁵ The authors collected their data in everyday conversation that included questions eliciting reference to the past (S. Stavrakaki, personal communication with L.S. Bos, April 24, 2013).

⁶ If the future is derived from the present via modal and aspectual features, then this is more demanding than the use of present itself. This may account for the substitution of future with present.

⁷ None of the participants took part in the study by Bastiaanse (2008) or Jonkers and de Bruin (2009).

⁸ The spontaneous speech data will be reported in a separate paper.

⁹ B10’s first language has been Dutch since age 12, before that she spoke German. F9 was bilingual French–Dutch from early age onwards: He had French parents but grew up in Flanders, where Dutch is the first language.

¹⁰ Eleven experimental verbs were regular (weak), and the practice items and seven experimental verbs were irregular (strong). Irregular (strong) verbs usually have a vowel change in the simple past; the participle is formed by the prefix ge-, followed by the stem with vowel change, followed by the suffix –en. The verbs were not controlled for factors such as regularity and frequency, because the pictures of the TART are used in a wide range of languages. The difference between regular and irregular verbs is not in the scope of the current work, but is under debate (e.g., Faroqi-Shah, 2007; Marusch, von der Malsburg, Bastiaanse, & Burchert, 2012; Penke & Westermann, 2006). For the sake of completeness, differential performance on regular and irregular verbs will be mentioned in a footnote.

¹¹ Two other conditions were tested ([modal + infinitive] and [inchoative + infinitive]). The total number of items on the test was 90. These constructions are irrelevant for the current research questions and are therefore ignored.

¹² Both the categories “non-past” and “past” had the subcategory “semantic paraphasia,” which included semantic paraphasias with the target verb inflection. Semantic paraphasias with non-target verb inflection were categorised according to the erroneous inflection, since the primary interest of the current study was time reference.

¹³ Other past constructions included regular inflection on irregular verb stem, irregular inflections on regular verb stems, incompletely realised participles containing the lexical stem, and the past perfect.

¹⁴ Adding the object sentence-final (not counted as an error) was done four times by F6, and 41 times by B9, similarly divided over the conditions.

¹⁵ Accuracy on regular and irregular verbs, respectively, for agrammatic speakers: 7–27% on simple past; 27–41% on periphrastic past: 54–51% on simple present. For fluent aphasic speakers: 46–62% on simple past; 71–63% on periphrastic past; 83–81% on simple present.

¹⁶ However the simple past appears around twice as often as the present perfect in the Spoken Dutch Corpus (2009), agrammatic speakers may sometimes exhibit a preference for verb forms that have a lower frequency of occurrence than other verb forms (Bastiaanse, Bouma, & Post, 2009).