A number of optical illusions have temporarily taken over the Internet in recent years, with the infamous Dress being perhaps the most notable example. In addition to offering an amusing distraction, these ocular deceptions also provide scientists with opportunities to learn about the nature of vision, the brain, and perception, which is why researchers have just invented a brand new illusion called "Scintillating Starburst".
Consisting of several concentric star polygons, the illustration causes viewers to perceive shimmering rays that emanate outwards from the center of the image, connecting each of the bisecting points between the various “braids”. Observing these illusory beams flicker in and out of existence is pretty trippy, and researcher Pascal Wallisch says that the image “illustrates how the brain 'connects the dots' to create a subjective reality in what we see, highlighting the constructive nature of perception.”
Describing the new illusion in the journal i-Perception, Wallisch and colleagues explain that the appearance of these fleeting bright lines may be attributed to the interplay between our central and peripheral vision. According to the study authors, the points at which braids intersect can appear to be bolder than the individual lines, and our peripheral vision lacks the resolution to discern that this is not actually the case. As such, our brains assume that these internodes represent bright spots, and fills in the gaps by drawing a bright line connecting them.
However, our foveal – or central – vision, is sharp enough to recognize that the bisecting points are no brighter than the rest of the image, and therefore tells our brains that there are no bright lines running through the diagram. As a result of these conflicting messages being sent by the peripheral and foveal visual systems, the confused brain adds in flickering bright lines that continually appear and then quickly vanish.
When experimenting with different variations of their illusion, the researchers found that people tended to experience the effect more intensely when they increased the width and contrast of the lines, as this enhanced the apparent brightness of the bisecting points. Adding in more polygons had a similar effect, as this created more bisections and therefore more shimmering rays.
In their write-up, the authors note that this type of illusion bears similarities to a number of other optical tricks, including the famous pincushion grid illusion, which causes viewers to see phantom lines crisscrossing the lattice diagonally. However, they insist that Scintillating Starburst differs from the pincushion grid sufficiently to be considered a brand new class of illusion.