Cross-linguistic transfer effects of verb-production therapy in two cases of multilingual aphasia

ABSTRACT

Background: Verb retrieval is challenging for monolingual and multilingual speakers with aphasia. Previous research on bilingual aphasia shows equivocal results of cross-linguistic transfer and inhibition.

Aims: This study explores the impact of verb-production treatment in the treated and untreated languages of two bilingual speakers with aphasia. The main goals were to explore treatment effects, possible cross-linguistic transfer effects and to investigate possible inhibition of the untreated languages.

Methods & Procedures: The participants were one trilingual speaker (Portuguese-Ronga-Norwegian) with nonfluent aphasia and one bilingual speaker (English-Norwegian) with fluent aphasia. They received two types of treatment: communication-based therapy and Semantic Feature Analysis. Treatment was conducted in Norwegian, a late-acquired language for both speakers. Treatment effects were measured in action naming tasks and narrative tasks in the treated language as well as the untreated languages.

Outcomes & Results: Overall, the participants responded positively to the verb production treatments. This was demonstrated at the lexical level and also in discourse production, especially in the treated, but also in the untreated languages. No inhibition of the untreated languages was found.

Conclusions: The data provide evidence for positive effects of verb-retrieval treatment provided in sentence contexts in a late-learned weaker language of multilingual speakers with aphasia. The treatments did not lead to an unwanted inhibition of the untreated language, which is an important finding for clinicians as well as for researchers. The results provide evidence for a shared conceptual network of the languages in bilingual speakers, supporting current models of bilingual language processing.

KEYWORDS:

• Bilingual
• aphasia
• cross-linguistic transfer
• inhibition
• verb treatment

Acknowledgements

We thank PN and DT for taking part in this study, and Ingvild Røste for conducting the treatments. We are also grateful to Pernille Hansen for help with the statistics.

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes

1. The terms narrative, connected speech, and discourse will be used interchangeably in the paper.

2. In this paper, the terms bilingual and multilingual will be used somewhat interchangeably. By not separating these two groups, the use of the cumbersome term bi- and/or multilinguals is avoided.

3. Ronga is a Bantu language spoken mainly in Mozambique. Assessment of this language is not included, as neither the Bilingual Aphasia Test nor the action-naming test exist in this language. Narratives were collected in Ronga, but we have not been able to find qualified assistants to transcribe and analyse the data.

4. For both participants, assessment of aphasia type and severity is based on the Bilingual Aphasia Test (Paradis & Libben, 1987) and clinical judgement, since the BAT does not provide information on aphasia type.

5. Information on the language use and the proficiency level of each of the languages was obtained with the Language Use Questionnaire (Muñoz, Marquardt, & Copeland, 1999) and part A of the BAT (Paradis & Libben, 1987) for both participants.

6. Also referred to as constraint-induced language therapy (CILT) or constraint-induced aphasia therapy (CIAT) (e.g., Berthier et al., 2009; Pulvermüller & Berthier, 2008).

7. Ronga belongs to the Niger–Congo language family and is structurally very different from Norwegian. Since Ronga was not assessed in this study, we do not know whether the treatment in Norwegian affected this language in any way.

Additional information

Funding

This project was funded by the Norwegian ExtraFoundation for Health and Rehabilitation through EXTRA funds: [Grant Number 2011/2/0279] and partly supported by the Research Council of Norway through its Centres of Excellence funding scheme, project number 223265.