Abstract
It has been argued that optic flow, the pattern of motion at the eye, is crucial for controlling locomotion. Insects are sensitive to the global pattern of optic flow and it has been shown that they often attempt to maintain flow symmetry when flying. The environments humans encounter, however, are often asymmetrical with different surface textures present in distinct regions of the scene. Previous research on humans has shown that temporal and spatial flow asymmetries can influence walking down straight corridors, but these effects are largely negated by the presence of a visible ground that indicates the path (i.e. splay information). To examine conditions more akin to those experienced when driving, we created a ground plane with three regions related to a visible bending road. The ground could have a distinct texture applied to the road, outside of the road bend, and inside of the road bend to create asymmetric flow field displays. Results showed that different textures on either side of a path did cause systematic errors in steering trajectories, broadly consistent with the reduction of flow asymmetries. This was also true when one region was static (either by removing the texture or counter-rotating the textured region to remove velocity vectors) with steering biased toward the static region. We conclude that spatiotemporal asymmetries can affect human processing of optic flow and lead to biased locomotor steering even when travelling on visible paths.
Meeting abstract presented at VSS 2013