Optical illusions have fascinated us for centuries. These intriguing images play with our perception, creating distortions or effects that defy reality. But why does our brain fall into the trap? These illusions reveal much about how our eyes and brains work together to interpret the world around us.
How do optical illusions work?
An optical illusion occurs when our brain interprets an image in a way that is different from reality. This can be due to several factors:
• Light and shadow: Contrasts often mislead our perception of shapes or depths.
• Colours and patterns: Complex patterns give the impression of movement or distortion.
• Cognitive expectation: Our brain tries to “complete” an image based on past experience.
Some famous illusions and what they reveal
• The famous blue and black (or white and gold) dress: This illusion shows how differences in colour perception can be influenced by perceived lighting and the physiology of our eyes.
• The Kanizsa triangle: You see a triangle that doesn't exist. This reveals your brain's tendency to “complete” missing shapes.
• The café wall: A checkerboard pattern gives the impression that parallel lines are tilted, highlighting how our brains deal with contrasts and angles.
What these illusions reveal about your vision
Optical illusions aren't just fun; they highlight the limits and strengths of our visual system. For example:
• If you're sensitive to contrast illusions, this could indicate a strong reactivity to changes in light.
• Colour-based illusions reveal how your eyes and brain interpret wavelengths of light.
Why explore these illusions?
Aside from providing entertainment, optical illusions can help scientists understand visual conditions such as astigmatism or macular degeneration. They also raise awareness of the unique way in which each individual perceives the world.
Try them out at home!
Discover some popular illusions and test your perception:
• Ouchi illusion: Can you see movement?
• Ebbinghaus circles: Which central circle looks bigger?
Optical illusions remind us that our vision is not just a matter of our eyes but also our brain's interpretation. So, the next time an illusion mystifies you, remember that your brain is only doing its job: decoding a complex world in the most logical way possible.
