No, Visual Illusions are not "Tricks"

I often encounter a number of arguments for veridical vision (vision that is an “accurate” reflection of the physical world —something akin to a camera) from realists. While this view can be heuristically useful at certain times or in some contexts, it is nevertheless a fundamental misconception about visual perception.

Often, visual perception demonstrations that allow us to “see ourselves see” are referred to as illusions or “tricks”. This implies that there is some veridical dynamic that is normally at play–but is then fooled by some clever stimulus (I do realize how funny this seems coming from a Trompe L’oeil painter). However such terms are colloquial misnomers that reveal common misconceptions.

While it is true that much of our cortex is devoted to vision (as much as 30% devoted to vision (more indirectly.)), and there are indeed contributions from optical mechanisms at the level of the eye that we can perceive, such resource allotment and device kinship does not imply a system of vision that operates via physical measurement. At present, visual perception is more correctly understood as a process of eliciting “useful information” from inherently ambiguous retinal cell firing patterns. To this point, anatomically, only 20% (some would argue less) of the neural pathways entering the LGN (a relay station along the vision pathway to the visual cortex) are coming from the retinas. The remaining 80% of input is coming from other regions (Gregory, 1998). In a sense, sensory “information” is coming FROM the brain, not bring transmitted to it. This would make perfect sense as we “perceive” three dimensions even though the patterns of the light which fall on the retina exist only in two, we compensate for blind spots, automatically correct distorted information, and erase extraneous images that cloud our view (optic disc, the nose, blood vessels within the eye, etc.) This does not mean in any way that we cannot create very convincing reflections of reality in artificial mediums (like painting or drawing)—in fact, understanding such concepts of vision can allow for very effective informed decisions for the modern visual artist.

For me, these concepts provide insights into an effort that is not about painting simply what I see or what I know—but rather, what I would like a viewer to know.

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