Measuring discourse coherence in anomic aphasia using Rhetorical Structure Theory

Abstract

Purpose: The existing body of work regarding discourse coherence in aphasia has provided mixed results, leaving the question of coherence being impaired or intact as a result of brain injury unanswered. In this study, discourse coherence in non-brain-damaged (NBD) speakers and speakers with anomic aphasia was investigated quantitatively and qualitatively.

Method: Fifteen native speakers of Cantonese with anomic aphasia and 15 NBD participants produced 60 language samples. Elicitation tasks included story-telling induced by a picture series and a procedural description. The samples were annotated for discourse structure in the framework of Rhetorical Structure Theory (RST) in order to analyse a number of structural parameters. After that 20 naïve listeners rated coherence of each sample.

Result: Disordered discourse was rated as significantly less coherent. The NBD group demonstrated a higher production fluency than the participants with aphasia and used a richer set of semantic relations to create discourse, particularly in the description of settings, expression of causality, and extent of elaboration. People with aphasia also tended to omit essential information content.

Conclusion: Reduced essential information content, lower degree of elaboration, and a larger amount of structural disruptions may have contributed to the reduced overall discourse coherence in speakers with anomic aphasia.

Keywords:

• discourse analysis
• aphasia
• speech-language pathology

Acknowledgements

This study is supported by a grant funded by the National Institutes of Health [NIH-R01-DC010398] to Anthony Pak-Hin Kong (PI) and Sam-Po Law (Co-I); and the Erasmus Mundus Joint Doctorate Fellowship IDEALAB to Anastasia Linnik. Special thanks to the staff members in the following organisations (in alphabetical order) for their help in subject recruitment: Christian Family Service Center (Kwun Tong Community Rehabilitation Day Center), Community Rehabilitation Network of The Hong Kong Society for Rehabilitation, Internal Aphasia Clinic at the University of Hong Kong, Hong Kong Stroke Association, Lee Quo Wei Day Rehabilitation and Care Centre of The Hong Kong Society for Rehabilitation, Queen Mary Hospital and Self Help Group for the Brain Damage. The authors would also like to acknowledge our subjects who participated, and Christy Lai, Lina Wong, and Winsy Wong for their assistance in data collection and processing.

Declaration of interest

The authors report no conflict of interests.

Supplementary material

Supplemental data for this article can be accessed at http://dx.doi.org/10.1080/17549507.2017.1293158

Additional information

Funding

This study is supported by a grant funded by the National Institutes of Health [NIH-R01-DC010398] to Anthony Pak-Hin Kong (PI) and Sam-Po Law (Co-I); and the Erasmus Mundus Joint Doctorate Fellowship IDEALAB to Anastasia Linnik.