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Illusions
Our brains interpret sensory information using our past experiences, expectations, and surrounding information. Occasionally, this results in an incorrect perception of what is happening. When there is a mismatch between expectations and reality, optical illusions occur.
In the checker shadow illusion, we believe that the squares labelled A and B are different colours, even though in reality they are identical.
This is because our interpretation of the checkered surface relies on our knowledge of checkered surfaces (alternating colours) and colour constancy (that colours do not change when they are in relative dark or light).
In the Ponzo illusion, we interpret the two yellow lines as being different lengths because of our expectation that as parallel lines get further away from us they visually converge (like railroad tracks).
In the Muller-Lyer illusion, the line segment bordered by inward facing arrows is perceived as longer than the line segment bordered by outward facing arrows, even though both are the same length.
This illusion does not occur in people who are raised in environments without right angles. It is a result of our expectations for inner vs. outer corners of objects.
Mark Yourself Question
- Grab a piece of paper and try this problem yourself.
- When you're done, check the "I have answered this question" box below.
- View the solution and report whether you got it right or wrong.
Practice: Optical Illusions
Why do most optical illusions occur?