Disentangling imitation and dyspraxia in individuals with autism
Ham, Heidi Elizabeth
MetadataShow full item record
Imitation deficits are well-documented in autism although the specific nature of these deficits is not completely understood. Researchers have attempted to account for imitation deficits within the context of cognitive theories of autism but these theories have not been successful in explaining all of the gestural disturbances reported in individuals with autism spectrum disorder (ASD). The types of gestural impairments along with error patterns observed in autism are similar to those reported in adult patients with limb apraxia. In this thesis, a neuropsychological account of apraxia was explored. A cognitive model of praxis processing that has been tested in adults with limb apraxia was adapted for a group of children with autism. An experimental battery of tasks was designed to assess the different levels of gestural processing following the cognitive model. The battery included seventeen different experimental tasks: nine tasks assessing the production of meaningful gestures across modalities (verbal, visual, tactile, and imitation); two tasks assessing the imitation of meaningless gestures; six tasks assessing gestural recognition and gesture comprehension. The main aim of the thesis was to determine if the gestural performance patterns identified in individuals with autism could be more parsimoniously explained by disorders of praxis processing than by the traditional cognitive theories of autism. More specifically the aims were: (1) Determine if an ASD group differs from a group of typically developing controls in their ability to imitate meaningful and/or meaningless gestures, (2) Determine if deficits in gesture production are task dependent (transitive, intransitive, pantomimes), (3) Determine if group differences in gesture production are better accounted for by underlying cognitive deficits in visual motor (VMI), visual perceptual (VP), and working memory abilities (listening recall, (LR) digit recall (DR) and word list matching (WLM), (4) identify the specific patterns of gestural impairments using a single case approach to analysis using results of recognition, comprehension, production and imitation tasks across gesture types. Experiments testing gesture imitation and gesture production across modalities employed a logistic regression approach to analysis which was designed to compare a group of individuals with autism to that of a typically developing control group. Five main findings emerged: (1) Individuals with autism performed more poorly in tasks of imitation and production across modalities than their typically developing peers; (2) Meaningful gesture imitation and production tasks were not performed equally, supporting the theory of task dependency; (3) The same cognitive variables predicting imitative success of meaningful gestures also predicted production success. An increase in visual perception and listening recall were associated with greater success; an increase in LR was also associated with greater success; (4) Different cognitive variables predicted imitation success of meaningless gestures. Listening recall was associated with increased success of hand imitation but not finger imitation. Finger matching was associated with higher performance of finger imitation but not hand imitation and this effect was slightly stronger in the TD group; (5) Results of the single case approach to analysis revealed that patterns of praxis processing were identified in individuals with autism that were similar to those of previously reported cases of limb apraxia. Ideational, ideomotor, and ideational with ideomotor praxic syndromes were all revealed. The results of this study confirm that the cognitive model of Cubelli and colleagues (2000) successfully predicted patterns of praxis processing in ASD thereby confirming that the deficit extends beyond imitation. Standard cognitive theories of autism were unable to accommodate all of the findings. The implications of these results and synthesis of dyspraxia and current autism theories are discussed.