Abstract
Purpose: Contemporary research in biological motion perception has generally been confined to point-light animations of human movement. Our experiments examine whether perception of novel, coherent motion sequences depicting animate creatures evokes similar neural responses as perception of human motion. Method: A new stimulus set (‘creatures’) was created using 3-D artificial evolution software (‘Framsticks’, http://www.frams.alife.pl). These stimuli depict animate beings, each with unique body configurations and unique manners of locomotion. Results from a rating experiment demonstrate that observers perceive point-light versions of these creatures as ‘alive’. Two blocked fMRI experiments compared neural activity for viewing moving creatures versus human motion. In a first experiment, observers viewed fully-illuminated animations of creatures and humans. In a second experiment observers viewed point-light animations of creatures, point-light animations of humans, and scrambled point-light animations motion-matched to the human animations. Results: Fully-illuminated animations of human movement produced greater BOLD response in STSp and ITS brain areas than creatures. The BOLD response in FFA did not differentiate between the two type of animations. Despite being rated as ‘alive’, point-light animations of creatures resulted in BOLD activity similar to that of scrambled sequences in areas selective for biological motion. Conclusions: These results suggest that perceived animacy is insufficient for optimally driving neural activity within brain areas selective to biological motion. Poorly selective neural responses for point-light creatures suggests that knowledge of body structure may be an important factor for activating these areas.