In conclusion, Hecht’s distinction between illusiond and illusionm and his criticism of the naïve illusion concept in vision research is interesting. When we become aware of illusions, when we suddenly recognize the virtual character of our subjective world, certain metacognitive processes are initiated that are a worthwhile subject matter for further investigation. In some sense they become part of the experience, and an important question is whether and how the two aspects of the experience interact. Nevertheless, Hecht also agrees that perceptual representations are relatively immune to top-down control, i.e., even in the rare cases in which the illusory character becomes manifest, the perceptual processes are mostly modular and impenetrable in nature. Therefore, the question of illusory representation can be tackled independently of the question of metacognitive awareness, and continues to be an important guide for research on visual processing. Apart from looking at the more conceptual question of the level at which the term “illusion” should be applied, which is moot to some degree, I have tried to provide examples of relevant illusiond research that has made progress on the question of how the brain processes visual information. Even for the underspecification problem, there is opportunity for valuable insight, which hasn’t been exploited to full potential yet in current research.