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Brett Fajen, Melissa Parade; The visual control of locomotion during interception and avoidance of moving objects. Journal of Vision 2012;12(9):186. doi: 10.1167/12.9.186.
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© ARVO (1962-2015); The Authors (2016-present)
Many locomotor tasks, including intercepting targets, avoiding obstacles, and selecting routes, involve interactions with moving objects. A simple strategy for intercepting moving targets is to move so as to keep the target at a fixed bearing angle. Likewise, moving obstacles can be evaded by moving so as to avoid keeping the obstacle at a fixed bearing angle. However, this model does not explain how direction and speed of locomotion are coordinated during interception, does not account for the physical extent of objects, and does not easily generalize to more complex environments with many moving objects. In this study, we consider an alternative model based on eyeheight-scaled information that specifies the locomotor speed needed to intercept or avoid moving objects. First, we test the prediction that manipulations of self-motion information influence the perceived walking speed needed to intercept a moving target. This follows from the fact that the information about required speed is found in the object-motion component of optic flow, which means that the self-motion component must be factored out. Subjects walked to intercept moving targets in a virtual environment viewed through a head-mounted display. Target speed and trajectory varied across trials. The influence of self-motion information was tested by manipulating subjects’ movements relative to the stationary background without affecting their movement relative to the moving target. We found small but statistically significant effects of self-motion information consistent with the prediction that movements were guided by information about required walking speed found in the object-motion component of optic flow. Second, we will show how this information can be used to (1) coordinate the speed and direction of locomotion during interception and obstacle avoidance, (2) avoid obstacles in a way that takes their extent into account, and (3) account for route selection in more complex environments.
Meeting abstract presented at VSS 2012
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