Symbolic Language Abilities for Aided Communication in Persons with Aphasia

Abstract

Aphasia is an impairment in the capacity to formulate and interpret symbolic language functions caused by focal brain damage. The compensatory approach to aphasia rehabilitation usually takes the form of augmentative and alternative communication (AAC) which provides communication strategies for supplementing, scaffolding, replacing or restoring natural speech. AAC for persons with aphasia (PWA) ranges from vocalizations, signs, or gestures (unaided communication), to writing, communication books, and speech-generating devices that utilize picture or graphic symbols (aided communication). In recent years, aided AAC that utilizes graphic symbols have been trialled in PWA and reports of their ability to combine single meaning symbols to form simple phrases and sentences to convey message has been on the high rise. Despite these positive outcomes, PWA poses several challenges towards learning and acquisition of AAC due to their inherent linguistic and cognitive impairments that affect the linguistic, operational, social and strategic competence required to use an AAC. An adequate understanding of strengths and resources available to PWA becomes important in planning AAC intervention. However, there is an insufficient number of researches involving AAC in PWA to enable our understanding of how symbolic language skills required to use a visual-based alternative communication system is affected by each type and severity of aphasia. Also, the intervention studies that gave evidence towards the ability of PWA to identify, categorize and sequence symbols to use aided AAC, often failed to show generalization of abilities. The lack of ability of PWA to use an AAC system for independent communication demands researchers to re-explore the skills required to these systems. Furthermore, there is a need to conduct such studies in India due to the large disparity between the country's small number of research done to guide clinicians to implement evidence-based AAC intervention and the large number of PWA who are potential candidates for AAC; given that India has the world's second-largest number of PWA. Thus, the present study investigated the symbolic language abilities required to use aided AAC in PWA. The symbolic language abilities studied included the ability to identify, categorize, and sequence symbols which was tapped using seven behavioural tasks designed using picture communication symbols (PCS). The study also explored the relationship between these symbolic language abilities and verbal language skills as well as non-verbal cognitive skills which were obtained from aphasia quotient and cortical quotient measures of test of aphasia in Malayalam. The study included 20 PWA (inclusive of 10 anomic aphasia and 10 Broca’s aphasia which formed subgroups of aphasia) and 20 age, gender, education-matched neurotypical adults as participants for the study. The comparison of performance between participant groups as well as within and across groups on the behavioural tasks, and the correlation between measures were performed using descriptive and inferential statistical analyses. The results of the study revealed that the performance of PWA and its subgroups were poorer than neurotypical adults. The study findings revealed that even persons with severe aphasia can identify, categorize symbols as well as sequence symbols to construct simple phrases and sentences to convey information. Supplementary analyses of the obtained data from the behavioural tasks showed that (a) grid size of the AAC display and grammatical category of referents have an effect on symbol identification in PWA, (b) performance on auditory categorization is better than visual categorization in PWA, and (c) the syntactic structure and semantic informativeness of sentences constructed using symbols by Broca’s aphasia was significantly less than anomic aphasia and neurotypical adults. It was observed that symbols facilitated word retrieval, improved verbal utterances and rectified phonemic paraphasias in PWA. In addition, a strong positive correlation was found between symbolic language abilities and verbal language abilities, as well as between symbolic language abilities and non-verbal cognitive abilities. The implications, limitations, and future directions of the study are discussed in detail.