Distortions of the local spatial-frequency power spectrum caused by motion blur may be used by the visual system to improve motion analysis (eg Barlow and Olshausen, 2004 Journal of Vision 4 415–426). We tested this hypothesis by measuring the error of perceived motion direction of moving patterns in the presence of random noncoherent motion manipulated to create different spatial power spectra. The results showed that error increased when the background power spectrum was similar to the motion power spectrum; however, when the background power spectrum had an anisotropy consistent with motion blur, the error was reduced. Shifting the power spectrum away from the motion power spectrum reduced the error.
