[Recovery of 3D structure from motion and its statistical efficiency]

In order to investigate characteristics of the "structure from motion" in noise, we compared performances of recovering a three-dimensional structure from motion (3D condition) with those of recovering a two-dimensional structure (2D condition). In addition, we adopted a statistical efficiency approach to analyze the results. We conducted two experiments where we presented to observers a pair of three dots corresponding to three apexes of triangles rotating around an axis projected onto the fronto-parallel plane. A gaussian noise was added to the area of each triangle for each stimulus frame. Observers were required to discriminate areas of two triangles perceived with moving dots. Main results were as follows: (a) Significant difference was found between the efficiencies for 3D condition and 2D condition. We obtained about 50% or less recovery (i.e., a ratio of the 3D efficiency to the 2D one) in Experiment 2. (b) When we removed the constraints, the human efficiency and the percent recovery decreased dramatically.