The Role of Attention in Biological Motion Perception: A Biased Competition Perspective
Date
2012-09-17
Authors
Safford, Ashley S.
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Abstract
The ability to recognize and understand the movements and actions of others is critical to everyday social interaction. Considering the ecological significance and efficiency of biological motion perception, it has often been described as an automatic or attention-free process. However, although perception of these complex stimuli may seem effortless, evidence suggests that attention does play an important role, especially when other stimuli are present. Even so, the nature of the relationship between biological motion and attention has not been well defined. The four experiments of this dissertation detail the relationship between attention and biological motion within the framework of the biased competition model of attention. The biased competition model proposes that attention acts by resolving the competition that arises when two or more objects occur simultaneously, in favor of the attended stimulus. Behavioral and event-related functional magnetic resonance imaging responses were measured while participants viewed point-light animations of human and tool motion under different attentional conditions. Results illustrated that the neural mechanisms underlying biological motion perception are strongly modulated by selective attention: when attention was focused away from biological motion, responses were reduced compared to when biological motion was selected by attention. Additionally, consistent with the biased competition model, the spatial proximity between concurrently presented items influenced the neural response to biological motion. While separation between simultaneously presented objects resulted in increased responses when attention was focused on biological motion, directing attention away from biological motion led to decreased neural responses when stimuli were separated. These results indicated that there is involvement of both object-based and spatial attention. Finally, expectations regarding specific object categories did not influence visual processing by preactivating neural responses in brain regions involved in processing biological motion. Together, the findings presented here lend further evidence for a critical role of top-down influences on the neural mechanisms underlying biological motion perception and indicate that this role is partially consistent with the predictions of the biased competition model.
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Keywords
Biological motion, Attention, FMRI, Biased competition, Vision, Perception