Abstract
The perception of human motion is a vital ability in our daily lives. Human movement recognition is often studied using point-light stimuli in which dots represent the joints of a moving person. Depending on task and stimulus, the local motion of the single dots, and the global form of the stimulus can be used to discriminate point-light stimuli. Previous studies often measured motion coherence for global motion perception and contrasted it with performance in biological motion perception to assess whether difficulties in biological motion processing are related to more general difficulties with motion processing. However, it is so far unknown as to how performance in global motion tasks relates to the ability to use local motion or global form to discriminate point-light stimuli. Here, we investigated this relationship in more detail. In Experiment 1, we measured participants’ ability to discriminate the facing direction of point-light stimuli that contained primarily local motion, global form, or both. In Experiment 2, we embedded point-light stimuli in noise to assess whether previously found relationships in task performance are related to the ability to detect signal in noise. In both experiments, we also assessed motion coherence thresholds from random-dot kinematograms. We found relationships between performances for the different biological motion stimuli, but performance for global and biological motion perception was unrelated. These results are in accordance with previous neuroimaging studies that highlighted distinct areas for global and biological motion perception in the dorsal pathway, and indicate that results regarding the relationship between global motion perception and biological motion perception need to be interpreted with caution.
Highlights
We constantly perceive movement from the world around us, from leaves being blown by a gust of wind, to people walking in the street
Low-level motion coherence threshold as measured in the random dot kinematograms (RDK) task ranged from 10% to 100% coherence, with a median of 26%
We investigated the relationship between biological motion processing and the perception of global motion coherence
Summary
We constantly perceive movement from the world around us, from leaves being blown by a gust of wind, to people walking in the street The former is related to bottom up processing and is predominantly stimulus driven: we integrate the motion of all leaves into the percept of their global movement. Random dot kinematograms (RDK) are often used to study the properties of global motion perception These RDK stimuli resemble a dense swarm of bees, and by integrating the local motion of all ‘bees’, it is possible to determine the general direction in which the swarm is flying. The discrimination of global motion is thought to rely on processing in area hMT/V5, as part of the dorsal visual stream. Braddick, O’Brian, Wattam-Bell, Atkinson, and Hartley (2001) found that neurons in hMT/V5 show greater activation to coherent than incoherent global motion, whereas in V1, for example, activation is higher for incoherent motion
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call