The Münsterberg figure and twisted cords.

The Münsterberg tilt effect can be explained by the effects of band-pass filtering in the visual system, supplemented by the principle that peaks and troughs in the filtered image are represented separately at the stage of orientation encoding. Circularly symmetric band-pass filtering of the Münsterberg figure reveals that both peaks and troughs along the mortar are oriented along lines that are slightly tilted with respect to the horizontal. The result is a Fraser twisted cord, which underlies the Münsterberg effect. We use the principle of the twisted cord to derive a new version of the Münsterberg effect.