Vision Sciences Society 2006
Volume 6, Number 6, Abstract 966, Page 966a doi:10.1167/6.6.966 http://journalofvision.org/6/6/966/ ISSN 1534-7362
Reflexive social attention elicited by biological motion
Yoshiya Mori Graduate School of Frontier Biosciences, Osaka University
Mikio Inagaki Graduate School of Frontier Biosciences, Osaka University
Lisa Wu Massachusetts Institute of Technology
Taijiro Doi Graduate School of Engineering Science, Osaka University
Eishi Hirasaki Graduate School of Human Sciences, Osaka University
Hiroo Kumakura Graduate School of Human Sciences, Osaka University
Ichiro Fujita Graduate School of Frontier Biosciences, Osaka University
Guessing where another individual is attending and preparing for his/her upcoming action is crucial for members of a social group. Experiments have shown that both monkeys and humans automatically orient their attention to the direction of another's head or gaze. Here we report that the walking direction of another individual also elicits a reflexive shift of visuospatial attention in monkeys and humans. We examined how the reaction time to peripheral visual targets was affected by a prior, brief presentation of a walking biological motion (BM) stimulus. This stimulus comprises dynamic displays of light points placed on the major joints of a moving human or animal. During the task, human and monkey subjects responded to a target point after the disappearance of BM stimulus and the fixation point. Throughout the task, the walking direction of the BM stimulus was not predictive of the target direction, and was irrelevant for performing the task. We found that reaction times in congruent trials, where the walking direction of the BM stimulus and the direction of the target appearance were the same, were significantly shorter than those in incongruent trials. This effect is distinct from other stimulus-driven attention in that the sudden onset of the BM stimulus directs attention to other locations. The attention mechanisms driven by BM may be part of the intentionality inference system that is suggested to be a substructure of the neural mechanism of reading another's mental state, termed "theory of mind".
Supported by grants from 17022025 and Takeda Science Foundation.