Abstract
Defined as the depth/width aspect ratio, metric shape is perceived when an object makes ≥45° continuous rotation in depth (Bingham & Lind, 2008). In this case, two sources of information are available to an observer: optic flow and image structure. Through motion—low spatial frequency signals—optic flow specifies depth structures and allows shape perception. Therefore, with strong optic flow, metric shape should be perceptible even when vision is blurred. Furthermore, when an object rotates, optic flow also calibrates image structure to make it spatiotemporally meaningful. In return, calibrated image structure preserves the depth structures specified by optic flow after motion ends. The combination of optic flow and image structure has been shown to engender efficient perception of object locations (Pan, Bingham, & Bingham, 2013, 2017) and daily events (Pan & Bingham, 2013), and is expected to enable accurate and stable perception of metric shape. We tested these predictions in two experiments. In Experiment 1, we used 0.2 Bangerter filters to create blurry vision and found that when target objects were rotating 60° back and forth, their metric shapes were accurately perceived by observers with or without the filters. In Experiment 2, observers with or without the filters viewed a random target object rotating 60° and waited for 0s, 5s, 15s, 25s, or 35s before they adjusted an outline on the monitor to match the cross-section of the target object. During the delay, observers either saw the stationary target object or a black screen. Errors were smaller when the image structure of target object remained available during the delay. In conclusion, we found that perception of metric shape is accurate and stable with strong optic flow, even when image structure is impaired. The findings are applicable to low vision rehabilitation, especially in regaining visual functions (such as visually guided grasping) with blurry vision.
Meeting abstract presented at VSS 2018