Subjective Contours
The images physically consist of 3 circles with pie shaped wedges removed and 3 angles formed from straight lines or 3 triangles. When you look at the images, you will likely see one triangle on top of another. The top triangle typically appears lighter, although the background is physically uniform. The triangular forms and the apparent lightness of the top triangle in comparison with the bottom one are subjective. Note that the illusion occurs with both colored and black/white stimuli. What in your visual system accounts for the appearance of the contours?
The subjective contours also appear when marked color differences segregate the parts of each image. What does this suggest about color in relation to form processing?
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