Date of Degree

10-2014

Document Type

Dissertation

Degree Name

Ph.D.

Program

Psychology

Advisor(s)

John J. Foxe

Sophie Molholm

Subject Categories

Behavioral Neurobiology | Clinical Psychology | Neuroscience and Neurobiology

Keywords

attention, autism, biological motion, development, EEG, electrophysiology

Abstract

Biological motion (BM) analysis and interpretation is a fundamental process of human neurocognition that has been only minimally explored neurophysiologically. In addition to its importance in understanding the underlying roots and development of social cognition, BM processing is a prime candidate domain for exploring the underlying etiology of social cognitive disorders such as the autism spectrum.

In an initial experiment, typical adults observed BM point-light displays of a human actor (UM) as well as their spatially scrambled counterparts (SM), in both an unattended distractor task as well as an explicit attention task. Results showed a neurophysiological response manifested as three phases of activity over parieto-occipital sites: an early (100-200 ms) automatic phase that was task-invariant; a mid-level activity (200-350 ms) that was amplified by attention; and a later phase of activation (400-500 ms) that only manifested when BM was explicitly attended.

In contrast, in follow-up experiments with typically-developing children (TDs), BM processing that distinguished UM, SM, and inverted motion (IM) occurred later (250 ms onward) and appeared as only one contiguous window of activation that was unaffected by attention. It was also observed that children with an autism spectrum disorder (cASD) demonstrated both typical BM behavioral ability as well as typical BM-related electrophysiological activity as manifest in the interactions between group and the three BM stimulus-responses (UM, IM, SM). Notably, all three stimulus-responses individually generated similarly distinct between-group effects from quite early (129 ms) suggestive of more general visual processing dysfunctions in the disorders. In addition, a more powerful secondary analysis detected between-group effects even in the differences between the responses evoked by the UM and SM conditions, suggesting the presence of specific BM-processing dysfunctions in ASD. The role of such sensory deficits in the development of social impairments in the disorders such as in theory-of-mind is discussed.

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