Conceptual and Lexical Factors in the Production of Speech and Conversational Gestures: Neuropsychological Evidence

Abstract

Parallel breakdown of gestures and speech following neurological damage supports the notion that ”... gestures and speech ... share a computational stage...” (McNeill, 1992) and emphasizes the role of neuropsychological approach for studying gestures. In this study patterns of conversational gestures were analysed in subjects with Alzheimer’s dementia, whose communicative performance indicated either primary lexical deficit or deficit in pragmatic/conceptual elaboration of discourse. Two gesture patterns were identified. The demented subjects with lexical deficit mostly produced iconic gestures which accompanied paraphasic expressions related to discriminating information. Conversely, the pragmatic/conceptual deficit corresponded to reduced production of iconic and increased production of deictic gestures. These findings indicate that the cognitive impairment underlying communicative deficit constrains the production of conversational gestures in brain-damaged patients. They also support the hypothesis that the early conceptual processes of speech production system play a central role in producing gestures.

This study has been supported by a PRIN Cofin-2000 Grant from MURST (Italy) to Sergio Carlomagno. This paper is the result of the joint research of the two authors. The first two paragraphs of Part I (Introduction) and Part 3 (Results and Discussion), however, have been written by Carla Cristilli, while the Abstract, the last two paragraphs of Part I (Introduction) and Part 2 (Methods and Subjects) have been written by Sergio Carlomagno.