Integrity and function of gestures in aphasia

ABSTRACT

Background: Gestures can provide an excellent natural alternative to verbal communication in people with aphasia (PWA). However, despite numerous studies focusing on gesture production in aphasia, it is still a matter of debate whether the gesture system remains intact after language impairment and how PWA use gestures to improve communication. A likely source for the contradicting results is that many studies were conducted on individual cases or in heterogeneous groups of individuals with additional cognitive deficits such as conceptual impairment and comorbid conditions such as limb apraxia.

Aims: The goal of the current study was to evaluate the integrity and function of gestures in PWA in light of cognitive theories of language–gesture relationship. Since all such theories presuppose the integrity of the conceptual system, and the absence of comorbid conditions that selectively impair gesturing (i.e., limb apraxia), our sample was selected to fulfill these assumptions.

Methods & Procedures: We examined gesture production in eight PWA with preserved auditory comprehension, no comorbidities, and various degrees of expressive deficit, as well as 11 age- and education-matched controls, while they described events in 20 normed video clips. Both speech and gesture data were coded for quantitative measures of informativeness, and gestures were grouped into several functional categories (matching, complementary, compensatory, social cueing, and facilitating lexical retrieval) based on correspondence to the accompanying speech. Using rigorous group analyses, individual-case analyses, and analyses of individual differences, we provide converging evidence for the integrity and type of function(s) served by gesturing in PWA.

Outcomes & Results: Our results indicate that the gesture system can remain functional even when language production is severely impaired. Our PWA heavily relied on iconic gestures to compensate for their language impairment, and the degree of such compensation was correlated with the extent of language impairment. In addition, we found evidence that producing iconic gestures was related to higher success rates in resolving lexical retrieval difficulties.

Conclusions: When comprehension and comorbidities are controlled for, impairment of language and gesture systems is dissociable. In PWA with good comprehension, gesturing can provide an excellent means to both compensate for the impaired language and act as a retrieval cue. Implications for cognitive theories of language–gesture relationship and therapy are discussed.

KEYWORDS:

• Aphasia
• gesture
• Interface Model
• Lexical Facilitation Model

Acknowledgments

We would like to thank the staff and patients at the Tabasom Stroke Rehabilitation center for helping us in the recruiting process. We also thank everyone in the Language and Cognition Lab at Koç University for their helpful comments on this research and Aylin Küntay for her constructive feedback on the findings.

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes

1. Farsi is a pro-drop language, so the absence of subject is not ungrammatical.

2. The Interface Model also posits that gesturing helps with syntactic packaging. Since the majority of PWA in our sample were Broca’s and produced agrammatic utterances, this prediction is not examined.