Time reference in nonfluent and fluent aphasia: a cross-linguistic test of the PAst DIscourse LInking Hypothesis

ABSTRACT

Recent studies by Bastiaanse and colleagues found that time reference is selectively impaired in people with nonfluent agrammatic aphasia, with reference to the past being more difficult to process than reference to the present or to the future. To account for this dissociation, they formulated the PAst DIscourse LInking Hypothesis (PADILIH), which posits that past reference is more demanding than present/future reference because it involves discourse linking. There is some evidence that this hypothesis can be applied to people with fluent aphasia as well. However, the existing evidence for the PADILIH is contradictory, and most of it has been provided by employing a test that predominantly taps retrieval processes, leaving largely unexplored the underlying ability to encode time reference-related prephonological features. Within a cross-linguistic approach, this study tests the PADILIH by means of a sentence completion task that 'equally' taps encoding and retrieval abilities. This study also investigates if the PADILIH’s scope can be extended to fluent aphasia. Greek- and Italian-speaking individuals with aphasia participated in the study. The Greek group consisted of both individuals with nonfluent agrammatic aphasia and individuals with fluent aphasia, who also presented signs of agrammatism. The Italian group consisted of individuals with agrammatic nonfluent aphasia only. The two Greek subgroups performed similarly. Neither language group of participants with aphasia exhibited a pattern of performance consistent with the predictions of the PADILIH. However, a double dissociation observed within the Greek group suggests a hypothesis that may reconcile the present results with the PADILIH.

KEYWORDS:

• Time reference
• past reference
• future reference
• encoding
• retrieval

Acknowledgements

We are grateful to all individuals who took part in this study. We also thank Fabiana Galiussi and Dimitra Arfani for helping with data collection and transcription, as well as two anonymous reviewers and the audience of the 16th International Clinical Phonetics and Linguistics Association (ICPLA) Conference (Halifax, Canada, 2016) and of the 54th Academy of Aphasia Annual Meeting (Llandudno, Wales, UK, 2016) for their useful comments and suggestions.

Declaration of interest

The authors report no conflicts of interest.

Notes

¹ The view that present and future reference do not involve discourse linking is debated (see, for example, Fyndanis, Manouilidou, Koufou, Karampekios, & Tsapakis, 2013, and references therein).

² Examples taken from Bastiaanse (2013: 250).

³ It is not common for people with fluent aphasia to show signs of agrammatism. Nevertheless, similar cases have already been reported in the aphasia literature (see, for example, Varlokosta et al., 2006).

⁴ Sentences were presented orally by the experimenter to the Greek-speaking participants and with the aid of a computer to the Italian-speaking participants. This was so because one of the persons who tested the Italian-speaking participants with aphasia (i.e. the 1st author) was not a native speaker of Italian. We recorded, thus, a native speaker of Italian who read out loud the experimental items (without the target verb phrases) and incorporated these audio files into a PowerPoint presentation.

⁵ Trial Order was scaled before entering mixed models (see Baayen, 2008).

⁶ We thank an anonymous reviewer for this suggestion.

Additional information

Funding

This research was supported by a Marie Curie Intra European Fellowship (awarded to V. Fyndanis) within the 7th European Community Framework Programme, project reference 329795, and by the Research Council of Norway through its Centres of Excellence funding scheme, project number 223265.