Examining the Idea of the "Blurry" Periphery

Here’s a fun fact (or two) that addresses a very common misconception about “blur” in regards to some representational efforts:

I have often encountered the idea that our peripheral vision is inherently "blurry.” This is actually not the case. The fact is that the peripheral region of our visual field is “spatially imprecise” compared to our central (or “foveal”) vision. We can demonstrate this with a simple graphic that places both “sharp” and “blurred” characters within our periphery (adapted from a wonderful demonstration by Margaret Livingstone in her book “Vision and Art: The Biology of Seeing.”)

Hold your gaze on either dot in the center. You should still be able to distinguish (significantly) between the blurry and the sharp without shifting your gaze. If the periphery was in fact inherently blurry, you would perceive both sets of characters that way. However, when you attempt to read either set of characters with your gaze still on a central dot—it is quite difficult-if not impossible. This is due to the "spatial imprecision” of this region.

We can experience a similar spatial imprecision within our center of vision by exploring equiluminance (different stimuli that hold the same value). For example, the word “equiluminance” written below may be difficult to read for most. This difficulty arises because the visual system diverges into two different processing pathways after a certain point. One system is very sensitive to changes in luminance (the “where”, or dorsal stream) while the other is very sensitive to changes in color (the “what”, or ventral stream.) In this case, the word equiluminance is written with a contrast via color (hue/chroma) changes but not luminance (value). This means our “what” system can make out the shapes due to changes in color, but has difficulty with the exact location of the letters as the “where” system has little to no luminance changes to use. The resulting sensation holds a certain level of spatial imprecision that is quite similar to what we experience in the periphery.

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