ABSTRACT
In this chapter, the author finds visual illusions puzzling partly because the underlying physiological mechanisms are unclear, but also because of mistaken general ideas about vision. He uses the term “picture theory of vision” to refer to the mistaken idea that seeing involves having an image in the head, rather than the extraction of information from an image. The idea that the Muller-Lyer effect is caused by neural blurring was advanced by Ginsburg and has recently received some support from Rogers and Glennerster. Ginsberg’s theory is that after blurring the outgoing-arrowhead figure, the ends of the line will extend into the acute angle formed by the arrowhead. Fourier analysis splits a waveform into simple components called “sine waves”. The technique is most familiar in acoustics, where a complicated sound pressure wave, for example, the sound from an orchestra, is split into pure tones.
