Illusion which is bigger

Which of the two red circles is bigger? The one on the right, right? In reality, the pair are identical. From a lifetime of looking at things, we remember that smaller items tend to be farther away, while larger ones are closer.

In this image, the brain reads the left ring of large, black circles as nearby and the right, smaller set as distant. Here is what the illusion typically looks like:. Almost everyone who sees this image will say that the central circle on the left is smaller than the one on the right. The illusion rests on the fact that the visual-attention system uses context to determine the size of objects.

The orange circle on the left is surrounded by larger circles, making it seem small by comparison. The one on the right is surrounded by smaller circles, making it seem big. Interestingly, adults who fall for the illusion visually tend not to succumb if asked to reach for the two objects.

Although their eyes are telling them that the circles are different sizes, their grip size is the same in both cases. This has been used as evidence that there are two separate pathways for vision in the brain, one used for identifying objects and the other used for action. The illusion feels fast and automatic yet is surprisingly susceptible to individual differences.

This Ponzo illusion uses the fact that human brain interpretes the image with perspective, however, it's just a simple 2D image. Which soldier is taller? This is a variation of Ponzo illusion which suggests that the human mind judges an object's size based on its background. If you like these brain teasers then feel free to share them with your friends. Share on Facebook. Most people perceive the central circle to be smaller, an effect known as the Ebbinghaus illusion.

Samuel Schwarzkopf and colleagues at University College London created a series of images in which the relative sizes of the two circles varied, and asked 30 volunteers to estimate which of the two was larger. From the scans, they were able to assess the size of the visual cortex. They found that people with a smaller visual cortex experienced the Ebbinghaus illusion more strongly.