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A great way to learn more about our brains and minds is to look at how we can trick them–that is, to see how we react to brain teasers and visu­al illu­sions.

Below are four fun opti­cal illu­sions that let us learn­ about our visu­al system…ready?

(answers and expla­na­tions at the bot­tom)

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1. Are the two orange circles above of the same size?

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2. Are there gray dots at the intersections of the white lines below?

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3. Does Lincoln’s face look normal?

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4. Where is the baby?

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ANSWERS AND EXPLANATIONS

1. The Ebbinghaus Illusion

The two orange cir­cles are exact­ly the same size, even though the one on the left seems small­er. This size dis­tor­tion may be caused by the size of the sur­round­ing cir­cles and their dis­tance to the cen­ter cir­cle.

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2. Hermann grid illusion

There are not gray dots in this grid. How­ev­er “ghost­like” gray blobs are per­ceived at the inter­sec­tions of the white lines. The gray dots dis­ap­pear when look­ing direct­ly at an inter­sec­tion.

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3. Does Lincoln’s face look normal?

It seems nor­mal but now, look at it upright: Lin­col­n’s eyes do not look quite right!

This is how the orig­i­nal image looked like, if seen upright.

Some neu­rons in the brain seem to spe­cial­ize in pro­cess­ing faces. And faces are usu­al­ly seen upright. When pre­sent­ed upside down, the brain no longer rec­og­nizes a pic­ture of a face as a face but rather as an object — neu­rons pro­cess­ing objects are dif­fer­ent from those pro­cess­ing faces and not as spe­cial­ized in face recog­ni­tion. As a con­se­quence, they (we) do not respond to face dis­tor­tions as well. This explains why we miss the weird eyes when the face is invert­ed..

4. Where is the baby?

Anoth­er great exam­ple of an illu­so­ry con­tour. The baby’s head is on the left, the baby’s feet are against the trunk of the tree on the right..

–> To keep learn­ing about your brain and mind, check out these Top 25 Brain Teasers, Games and Illu­sions, for Teens and Adults of Any Age.