Before revision: Second-order motion perception When the moving contour is defined by contrast, texture, flicker , or any property that does not lead to a rise in brightness or motion energy in the stimulus' Fourier spectrum , that motion is referred to as second-order motion .
After revision: Second-order motion perception Second-order motion is when the moving contour is defined by contrast, texture, flicker or some other quality that does not result in an increase in luminance or motion energy in the Fourier spectrum of the stimulus .