Optical Illusions Quiz: 15 Fascinating Questions
Our eyes deceive us more often than we think! From the Müller-Lyer illusion to Escher's impossible prints, discover the fascinating secrets of visual perception.
🏅 Best score: –
Frequently asked questions: Optical Illusions
A preview of what awaits you in this optical illusions quiz: 15 multiple choice questions, each with a detailed explanation so you can learn while you play. Here are a few sample questions (and their answers, so no cheating before you play!).
In the Müller-Lyer illusion, what do we wrongly perceive?
Answer: Lines of different lengths when they are actually equal. The Müller-Lyer illusion shows two lines of the same length, but the arrowheads at their ends give the impression that one is longer than the other. Discovered in 1889, this illusion shows how our brain interprets depth cues.
What causes a mirage in the desert?
Answer: The refraction of light by layers of air at different temperatures. A mirage is caused by the refraction of light as it passes through layers of air at different temperatures. The hot air near the ground bends the light rays, creating an inverted image of the sky that looks like a puddle or a lake.
Why can two identical colours look different when they are surrounded by different colours?
Answer: Because of simultaneous contrast, a mechanism of relative perception in the brain. Simultaneous contrast is a phenomenon in which our brain perceives a colour differently depending on the colours around it. Our visual system works by relative comparison rather than absolute measurement, which explains many colour illusions.
What happens when you stare at a coloured image for 30 seconds and then look at a white surface?
Answer: You see an afterimage in complementary colours. When you stare at a colour, the photoreceptor cells in the retina become fatigued. When you then look at a white surface, the cells that are not fatigued dominate and you perceive the complementary colours: red becomes cyan, blue becomes yellow, and so on.
The Adelson checker shadow illusion is a famous illusion. What does it demonstrate?
Answer: That two squares of identical colour look different because of the shadow. In the Adelson checker shadow illusion (1995), two squares on the board are exactly the same shade of grey, but the shadow cast by a cylinder makes one look light and the other dark. This demonstrates that our brain automatically corrects for brightness according to context.
Fancy another challenge? Discover all our free science quizzes or browse the latest quizzes. And to go from theory to practice, explore our science kits at Science Gifts.