Abstract/Summary

Aphasia is an acquired neurological impairment characterised by disruption to language functions. Beyond language, there is increasing agreement that the broader cognitive profile of aphasia can influence the manifestation of linguistic impairment, and additional cognitive deficits act as barriers to therapy. This thesis explored two important cognitive abilities for language and aphasia therapy-executive control and learning. The studies addressed the following questions: ( l) what is the profile of both executive control and learning abilities in anterior lesion aphasia, (2) what impact do language stimuli have on task performance for these abilities, and (3) how are language, executive control, and learning abilities associated with one another. Participants with anterior lesion aphasia and controls completed a series of behavioural executive control (Chapter Two) and learning (Chapter Three) tasks. A comparison of verbal and reduced verbal task versions was also carried out to investigate the impact of language on performance. Finally, the relationships between executive control, learning, and language performance were explored (Chapter Four). Findings revealed that the participants with aphasia (PW A) demonstrate a generalised cognitive slowing for executive control tasks, accompanied by specific impairments to switching and updating of working memory abilities. Executive control abilities did not vary across verbal and reduced verbal domains, supporting a domain-general account of these abilities. PWA were able to learn familiar and unfamiliar stimuli, but more slowly and ultimately below the level of control participants. When there was within task variation in the difficulty of verbal stimuli to be learned, PWA showed markedly poorer learning. Finally, there were significant associations between language, executive control, and learning abilities-suggesting the cognitive-linguistic profile in anterior lesion aphasia is interactive and complex. Taken together, findings reveal important insights into the broader cognitive-linguistic profile of anterior lesion aphasia and the theoretical and therapeutic implications for these are considered.