Kāpēc mūsu smadzenes krīt uz optiskajām ilūzijām?

A: Our brains engage in optical illusions because they perceive the world by using contextual information, shortcuts, and predictions. Among other patterns, the brain assumes that light comes from above, fills in missing edges, and exaggerates contrasts.

While these tricks help us navigate the world, they sometimes also lead to rational errors, where the brain interprets ambiguous information in a way that deviates from physical reality. For example, identical colors can look different against different backgrounds, and lines of the same length can appear unequal when framed differently.

A new study in Nature Neuroscience has taken this picture a step further. The researchers studied how the brain processes illusory contours, including shapes like the Kanizsa triangle, where we see edges that aren’t there. Using advanced imaging and optogenetics in mice, the researchers found that special neurons in the primary visual cortex called IC-encoders respond to these illusory shapes as if they were real edges. IC-encoders do this by integrating predictions from higher brain areas and relaying them to the brain, a process in which the brain fills in the missing details to create a coherent whole.

When scientists stimulated these neurons, the brain created the illusion even without a visual stimulus, showing that illusions simply “hacked” the way perception normally works: by combining partial evidence with prior expectations to infer the most likely picture.

“Sensory systems are constantly confronted with incomplete or ambiguous sensory information,” the researchers wrote in their paper. “In these situations, successful perception depends on sensory inference.”