How this works:
Pretty much all of your high-resolution optical neurons are concentrated in the fovea, the bit of your retina that corresponds to the centre of your vision.
Most of what you “see” in your peripheral vision is actually constructed within the brain, based upon context and memory.
In normal life, your eyes make constant saccades; small shifts of direction that move the fovea across the image, allowing your brain to update and refine the peripheral construction.
When you consciously lock your gaze, this stops happening, and the accuracy of the peripheral construction reduces. With gaze locked on the centre of the image, your brain bases its construction on the patterns at the edge of the fovea, which don’t have dots.
