Inverted and Imagined Biological Motion
Inverting point-light animations destroys the perception of biological motion (Sumi, 1984, Ahlstrom et al., 1997, Pavlova et al., 2000).
Neural activty on posterior STS was highest when the animations were presented upright, and lower when the animations were presented upside-down. Neural activity was always higher than that found when viewing scrambled motion.
Visual areas are also active during mental imagery of visual stimuli (Goebel et al., 2000). We asked observers to passively view biological motion sequences, and alternately to imagine the biological motion.
When we compared the corresponding activity levels we found higher signals when observers viewed the motion sequences than when they imagined the motion, though mental imagery always resulted in higher activity levels than the resting baseline.