Recognition affects the perception of apparent motion

Purpose. Research indicates the perception of apparent motion can be influenced by viewers' knowledge of how objects move in the environment. Shiffrar and Freyd (1990) suggested “biological” apparent motion is unique when they reported the perception of apparent motion for human figures was different from inanimate objects. We investigated whether this effect is due to the biological nature of the stimuli or due to the stimuli being recognized as familiar objects. Methods. In two experiments, ambiguous apparent motion displays were created by alternating between two pictures of an object on either side of a wall. Objects could be perceived to pass through or around the wall. Participants reported which path of motion they perceived. Degraded versions of the stimuli were also used to test whether recognition of the objects influenced the extent to which the physically possible, “around” path was seen. Results. Participants reported seeing the physically possible path of motion for both objects capable of movement in the environment and objects not usually seen in motion. Participants did not report seeing the physically possible path with the degraded versions of the objects. Conclusions. The apparent motion effect previously only found with human stimuli can be found with non-human stimuli, provided they depict familiar objects in the environment. The results suggest when stimuli are recognizable objects, observers use knowledge of how objects interact to interpret ambiguous apparent motion displays. ShiffrarM.FreydJ.(1990). Apparent motion of the human body. Psychological Science, 1, 257–264.