Abstract
Biological motion (BM) perception under selective attention is supported by a network of regions including the occipito-temporal, parietal, and premotor cortices. Considering the effortless processing and social importance of BM for humans, it can be assumed to occur automatically. Consistently, Thornton and Vuong (2004) showed that task-irrelevant BM stimuli at the periphery impaired the performance at the fovea; indicating incidental processing of BM stimulus. Another study examining retinotopic mapping of BM stimuli showed distinct maps for BM processing under and away from attention (Saygin & Sereno, 2008). However, the neural underpinnings of how BM is processed when attention is directed away from it lacks thorough examination. In the current study, we investigated whether the BM would be processed when shown away from the selective attention through an attentional load paradigm. Participants (N=31) underwent an fMRI study in which they performed an attentionally demanding visual detection task at the fovea while intact or scrambled point-light displays of BM were shown at the periphery. Our results showed the main effect of attentional load in fronto-parietal regions; whereas, the main effect of distractor was present in occipito-temporal regions. More importantly, in the presence of task-irrelevant peripheral BM stimuli, the motion-sensitive areas in the occipito-temporal cortex were activated even when participants attended at the fovea. Furthermore, MVPA results showed the decrease in the number of regions that could decode BM under high compared to low attentional load, indicating the attentional load modulation on BM processing. ROI results have expanded this finding by showing that the attentional load modulation of BM were the strongest in occipito-temporal regions compared to parietal and premotor cortices in both left and right hemispheres. In conclusion, BM was found to be processed within the occipito-temporal cortex when shown away from the selective attention; and was modulated by attentional load.