Biological motion cues aid identification of self-motion from optic flow but not heading detection
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© 2017 The Authors.
When we move through the world, a pattern of expanding optic flow is generated on the retina. In completely rigid environments, this pattern signals one's direction of heading and is an important source of information for navigation. When we walk towards an oncoming person, the optic environment is not rigid, as the motion vectors generated by the other person represent a composite of that person's movement, his or her limb motion, and the observer's self-motion. Though this biological motion obfuscates the optic flow pattern, it also provides cues about the movement of other actors in the environment. It may be the case that the visual system takes advantage of these cues to simplify the decomposition of optic flow in the presence of other moving people. The current study sought to probe this possibility. In four experiments self-motion was simulated through an environment that was empty except for a single, walking point-light biological motion stimulus. We found that by using biological motion cues, observers were able to identify the presence of selfmotion despite the lack of stable scene information. However, when estimating heading based on these stimuli, the pattern of observer heading estimates could be approximately reproduced by computing the vector sum of the walker's translation and the stimulated selfmotion. This suggests that though biological motion can be used to disentangle self-motion in ambiguous situations, optic flow analysis does not use this information to derive heading estimates.
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Riddell, Hugh ; Lappe, M. (2018)© The Author(s) 2018. The ability to navigate through crowds of moving people accurately, efficiently, and without causing collisions is essential for our day-to-day lives. Vision provides key information about one’s own ...
Mayer, K.M.; Riddell, Hugh ; Lappe, M. (2019)© 2019 American Psychological Association. The concurrent processing of optic flow and biological motion is crucial for navigating to a destination without colliding with others. Neuroimaging studies and formal models ...
Riddell, Hugh ; Li, L.; Lappe, M. (2019)© 2019 Association for Research in Vision and Ophthalmology Inc. We investigated whether biological motion biases heading estimation from optic flow in a similar manner to nonbiological moving objects. In two experiments, ...