What if the shapes you think you see are actually distorted illusions created by your brain?

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The underlying mechanism in our brain that causes images in our peripheral vision to become distorted

Dr Chandril Chugh, the director of Good Deed Clinic and a senior consultant neurologist, tells indianexpress.com, “When you focus on a central point, images in your peripheral (side) vision can appear distorted because your brain processes them differently. The center of your vision is sharp and clear, but your peripheral vision is less detailed. Your brain fills in the gaps, often leading to blurry or distorted images.” 

The fusiform face area (FFA) and visual cortex are key brain regions involved. They process facial features, but when faces appear briefly in peripheral vision, the brain struggles to piece them together correctly, causing the warped effect.

He continues, “This happens because your peripheral vision is designed to detect movement and large shapes, not fine details. Rapid eye movements also blur what’s on the side. The brain prioritises detecting motion in your periphery, which can make things appear distorted or out of focus. The phenomenon is called peripheral distortion or peripheral drift illusion.”

This is a learned evolutionary response, mentions the neurologist. “In the early days when we used to hunt in the forest, it was important to stay focused on the prey or the target and yet be aware of the threats from other predators in the jungle. Hence, the vision evolved to focus at the center and detect motion on the periphery while sacrificing clarity and focus in that field.”

Peripheral vision is dominated by rod photoreceptors, which are more sensitive to motion and low light but cannot detect fine details or colours. (Source: Freepik)

Specific brain regions or visual processing pathways responsible for creating these distortions 

“Certain brain regions and visual processing pathways distort what we see. Foveal vision, which dominates the center of our visual field, is sharp and detailed due to its high concentration of cone photoreceptors. These are specialised for fine detail and colour perception,” addresses Dr Chugh.

Peripheral vision, however, is dominated by rod photoreceptors, he says, which are more sensitive to motion and low light but cannot detect fine details or colours. The brain prioritises motion and large shapes in peripheral vision, often leading to less precise or distorted visual information from this area.