This illusion is a variation of the “Scintillating Grid Illusion.” It’s a fascinating example of how our perception can differ from reality, particularly in terms of how our central and peripheral vision interact.
This illusion has a grid of gray lines with 12 black dots at 12 intersections. However, when you look directly at one of the black dots, the others seem to vanish or flicker in and out of your peripheral vision, making it virtually impossible to perceive all the black dots at once, despite knowing they are there.
The underlying explanation lies in the limitations of our visual processing system. When we focus on one point, our central vision is excellent and allows us to see fine details. However, our peripheral vision is less precise, especially for distinguishing small objects or changes in contrast.
In the case of this illusion, when you focus on one black dot, your brain relies on the surrounding pattern (the gray lines) to make assumptions about what exists in your periphery. Since the majority of the pattern is gray lines, your brain assumes that the areas outside your central focus also consist mainly of gray lines. This results in the surrounding black dots seeming to disappear or flicker.
This optical illusion underscores how our brain often takes shortcuts in processing visual information by making assumptions based on patterns, context, and prior knowledge, sometimes leading to perceptual errors. It’s an impressive testament to the complexities and occasional shortcomings of our visual system.