Interference in Ebbinghaus Illusion stimuli

When adding two or more visual stimuli there may take place interference between their Fourier Transforms. Such interference may not only cause a uniform reduction in the amplitudes but may also alter the profile of the distribution. Here is shown how adding surrounding stimuli to a solid disk or thin circle may cause the amplitude spectrum to be altered. Spatial frequency and spatial size are related. Thus, interference may be related to the altered appearance of spatial size as experienced in some visual size illusions. Interference takes place in the stimuli and is unrelated to vision, i.e., it occurs even if the stimuli are not being seen.