Which of the following best explains why brightness illusions occur when viewing visual stimuli?

• A. Brightness illusions occur because the retina processes all light intensities equally.
• B. Brightness illusions are due to the presence of only rod cells in the human eye.
• C. Brightness illusions result from the brain's interpretation of relative luminance rather than absolute luminance.
• D. Brightness illusions are caused by the eye's inability to detect color differences.

Answer: (C)

Verified step by step guidance

1. Step 1: Understand that brightness illusions are visual phenomena where the perceived brightness of an area differs from its actual luminance due to contextual influences.
2. Step 2: Recognize that the retina does not process all light intensities equally; instead, the brain interprets signals from the retina to construct our perception of brightness.
3. Step 3: Note that rod cells are responsible for vision in low light and do not explain brightness illusions, which occur under normal lighting conditions involving both rods and cones.
4. Step 4: Realize that brightness illusions arise because the brain interprets relative luminance—how bright an area is compared to its surroundings—rather than absolute luminance values.
5. Step 5: Conclude that the best explanation is that brightness illusions result from the brain's interpretation of relative luminance, not from retinal processing limitations or color detection issues.