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Incredible Illusions

Herring Illusion

Distorting Reality

This diagram was first published in 1861 by Ewald Herring, and the illusion is named after him. It is similar to the Zollner Illusion and the Titchener Illusion. All these illusions demonstrate how geometrical relationships can seem to be distorted by their background (a lined background can make circles, squares and triangles seem distorted too).

The straight lines in the illusion appear to bow out in the centre. This may be because you interpret the radiating lines in terms of depth, seeing the central spot in the Herring diagram as being further away than the edges. As a result, you believe that the heavy black lines must be further away in the centre as well. Because the heavy black lines are the same thickness at the centre as at the edges but are further away, your brain thinks they must be more widely spaced at the centre.

A glimpse into the brain

Illusions like this one can tell us a lot about the way the brain interprets the things we see. The fact that people are fooled by visual illusions tells us that we do not just see what is out in the world. Instead, our brain takes information about what we see and simplifies it in ways that usually make it mean more. In the case of visual illusions, the brain gets it wrong.

Our brain uses the experiences we have had in the past to decide what is likely to be happening. Usually, it would be right to think objects that are further away must be more widely spaced. Because this is usually true, the brain makes this difference even bigger to help us understand what is going on. In this case, the middle is not really further away. The brain has made up a difference (the bending lines) when in reality there is none.

The Wundt Illusion

There are many illusions that are similar to the Herring illusion. The one on the left is called the Wundt Illusion because it was first drawn by the famous psychologist, William Wundt. This illusion is the exact opposite of the Herring illusion. The lines look as if they bow in at the middle. The middle of the Wundt diagram looks closer to you than the top and bottom. For this reason, your brain thinks the lines in the middle must be thinner and closer, so it exaggerates this imaginary perspective.