Acute angle enlargement and the Zoellner illusion.
The direction rather than the magnitude of the Zoellner illusion was assessed for intersect angles greater than 40 degrees. Data support the illusion's description as an instance of the principle of acute angle enlargement.
D005556:Form Perception; D006801:Humans; D007088:Illusions; D009903:Optical Illusions; D009949:Orientation; D010364:Pattern Recognition, Visual