PERCEIVED MOTION IN THE VECTOR SUM DIRECTION

The visual system is known to extract both Fourier (e.g. contour) and non-Fourier (e.g. texture boundary) motion signals from moving patterns. Recent evidence suggests that both Fourier and non-Fourier motion signals are involved in the analysis of rigid two-dimensional image motion. To determine how these signals are combined, we have measured perceived directions for plaids composed of either two non-Fourier components or one Fourier plus one non-Fourier component. In all cases the visual system combines these components to produce perceived motion in the vector sum direction; even when this deviates by as much as 53 deg from the intersection of constraints direction. This result was predicted by a model for pattern motion that combines Fourier and non-Fourier component motion signals using a vector sum operation.