Heading Perception Depends on Time-Varying Evolution of Optic Flow

Retinal optic flow during natural locomotion

“…Much of the work on optic flow either implicitly or explicitly assumes that optic flow is primarily relevant to steering to a distant goal, and so the experimental simuli tend to use use constant velocity straight line motion that is poor represenation of the visual motion stimulus experienced during natural locomotion.Some work has suggested that heading estimates rely on information accumulated over time (W. H. Warren et al, 1991;Grigo & Lappe, 1999;Layton & Fajen, 2016). In partcular, recent work by Burlingam and Heeger (Burlingham & Heeger, 2020) demonstrates that instantaneous optic flow is insufficient for heading perception in the presence of rotation, and showed that heading judgments in the presence of rotation depend on the timevarying evolution of the flow (that is, the retinal acceleration field). Althrough, their stimuli did not mimic the kind of time variations generated by natural gait patterns, their finding that observers are sensitive to the temporal derivative of the retinal velocity field has an interesting relationship to the present discussion of divergence and curl.…”

“…However, there is disagreement on whether heading perception is based on the instantaneous flow field, or instead based on some measure of the way the flow patterns change over time (Cutting & Springer, 1992;W. H. Warren, Blackwell, Kurtz, Hatsopoulos, & Kalish, 1991;Burlingham & Heeger, 2020;Li & Cheng, 2011).…”

Heading perception and the structure of the optic acceleration field

“…Likewise, in computer vision, nearly all camera motion estimation methods explicitly rely on instantaneous optic flow, i.e., they take two video frames or one optic flow field as input. Optic flow evolves over time, however, and this evolution contains information about heading [1,7,8,9,10,11,12,13]. A recent psychophysical study of human perception demonstrated that instantaneous optic flow is insufficient for accurate heading estimation, and that time-varying evolution of optic flow is necessary [1].…”

“…Optic flow evolves over time, however, and this evolution contains information about heading [1,7,8,9,10,11,12,13]. A recent psychophysical study of human perception demonstrated that instantaneous optic flow is insufficient for accurate heading estimation, and that time-varying evolution of optic flow is necessary [1]. Based on this experimental finding, we proposed the "optic acceleration hypothesis" -that the brain computes heading from optic acceleration, the temporal derivative of optic flow.…”

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Visual estimation of heading in the human brain is widely believed to be based on instantaneous optic flow, the velocity of retinal image motion. However, we previously found that humans are unable to use instantaneous optic flow to accurately estimate heading and require time-varying optic flow (Burlingham and Heeger, 2020). We proposed the hypothesis that heading perception is computed from optic acceleration, the temporal derivative of optic flow, based on the observation that heading is aligned perfectly with a point on the retina with zero optic acceleration.

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