Comparison of motion and stereopsis: Linear and nonlinear performance

To address the issue of whether the luminance-dependent (linear) and contra st-dependent (nonlinear) processes in stereo and motion have a common compu tational basis, we compare both carrier-dependent and envelope-dependent pe rformance for these two modalities by using the same stimulus and task: two -flash apparent motion/depth for a wide range of displacements. We do this for different densities, bandwidths, contrasts, spatial frequencies, and ex posure durations. The results suggest that there is concordance not only be tween the luminance-dependent (linear) processes of motion and stereo but a lso between the envelope-dependent (nonlinear) processes of both modalities . Only one exception was found, but we show this to be amenable to an expla nation based on a different contrast dependence for the nonlinear mechanism s of stereo and motion. This suggests that the computational basis of linea r and nonlinear processes may be similar for stereopsis and motion. (C) 199 9 Optical Society of America [S0740-3232(99)02405-9].