Psychology Seminar: Burcu Ayşen Ürgen (Bilkent University)
Top-down and bottom-up processing of biological motion in the human brain
Burcu Ayşen Ürgen (Bilkent University)
November 2, 13.00-14.00
Visual perception of the body movements of other living things (aka biological motion) is critical in many tasks ranging from survival in the wild to communication and interaction in social life. Perception of biological motion is supported by a network of regions in the occipitotemporal, parietal and premotor cortex in the primate brain. However, most studies to date studied BM under attention tasks, and how it is processed when attention is directed away lacks thorough examination. A handful of human behavioral studies show that when presented as a task-irrelevant distractor in the periphery, BM impairs performance on a task at the fovea. In the present study, we investigated whether the brain regions that process BM are recruited when attention is directed away from BM and how attentional load at the center modulates this processing. Human participants underwent a functional MRI study in which they performed an attentionally demanding task at the fovea while BM in the form of point-light displays was presented in the periphery as distractors. We manipulated the attentional load at the center. Univariate analysis and MVPA show that frontoparietal attentional regions were more active when the attentional load was high than when it was low as expected. More importantly, we found that motion-sensitive areas in the occipitotemporal cortex were recruited in the presence of task-irrelevant BM stimulus even when attention was directed away from it. Furthermore, during the low attentional load condition, BM-related activation was stronger than in the high attentional load condition, suggesting that if there are available attentional resources, they can be allocated to even task-irrelevant distractors, consistent with load theory. Thus, our results show that BM can be processed in the periphery even when it is not the focus of attention, and this process is modulated by the attentional load of the perceiver.
Meeting ID: 962 0179 1766