An investigation of the relationship between conceptualisation and non-linguistic communication: Evidence from drawing production in severe aphasia

Many people with aphasia have difficulty understanding and producing the language of events, i.e. verbs and sentences. One proposal is that language production difficulties in some individuals may reflect impairment to the processes that construct event representations in a language-appropriate way. This has been termed "thinking for speaking" (Slobin 1996), or "conceptual preparation" (Levelt, Roelofs and Meyer 1999). This study aims to extend understanding of the relationship between event conceptualisation, event communication and language impairment in severe aphasia. Evidence from a number of sources suggests that several aspects of conceptual preparation may be shared by linguistic and non-linguistic communication modalities. This thesis examines the ability of seven individuals with severely restricted linguistic output to communicate about events using the non-linguistic medium of drawing. The experimental investigation involves a detailed statistical and qualitative analysis of event drawing in response to short video clips and linguistic descriptions. For each participant, event drawing performance was compared with control data and with the results of other event processing and language assessments. Five participants showed problems with conceptual preparation, reflecting difficulties in the schematisation of events for the purpose of communication in general. This suggests that event conceptualisation difficulties should be considered as a possible underlying source of deficit for these individuals. Two participants showed intact event conceptualisation, suggesting a linguistic source of their difficulties. The findings also revealed a correlation between event conceptualisation problems and the nature and extent of individuals' language impairments, suggesting that there may a reciprocal relationship between the two. The theoretical and clinical implications of these findings are discussed. This study extends understanding of the consequences of impaired event processing on event communication and suggests a novel and theoretically motivated means of examining the underlying event conceptualisation and communication abilities of people with severe aphasia