Your eyes are amazing tools that help you see the world around you, but did you know there’s something they can’t see? It’s called your blind spot. Here’s a fun way to find it: close your left eye, look at a crosshair with your right eye, and slowly move your head closer or farther from the screen. At some point, a dot will disappear! This happens because the back of your eye has a spot where nerves and blood vessels connect, and there are no cells to detect light there. That’s your blind spot!
Now, let’s add a line through the image and try again. You’ll notice that your brain fills in the missing part, making it look like the line is continuous, even though there’s a gap in your vision. Here’s another fun trick: look at this picture with 12 black dots. Can you see them all at once? Probably not! Your eyes focus on one point, and your peripheral vision isn’t as sharp. Your brain fills in the gaps based on patterns it recognizes, so you might miss some dots until you look directly at them.
Check out these two rectangles. They seem to flash at the same time, but they actually don’t. If we move them just a little, you’ll notice they flash out of sync again. The way things around an object look can change how you see it, even if it’s not accurate.
Look at these flashing squares. Did you notice the middle square isn’t flashing at all? When we remove the outer square, you see it’s just a solid color. Try reading the sentence inside it. Did you spot the extra word? Your brain often skips over small mistakes because it focuses on understanding the whole sentence quickly rather than perfectly.
Here’s another cool illusion: stare at the middle dot in this picture. When the image isn’t moving, the colors change quickly. But when it starts rotating, the color change seems to slow down or disappear. Our eyes and brain have evolved to make quick assumptions based on what we’ve learned and expect to see. These illusions play with that ability.
Our brains are designed to process information quickly. Instead of focusing on every tiny detail, which would be overwhelming, they make educated guesses. This helps us react faster and make quick decisions, which is important for survival. For example, if you stare at a halo long enough, your brain might make it disappear because it assumes the information isn’t changing or important.
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Close your left eye and focus on a crosshair with your right eye. Slowly move your head closer or farther from the screen until a dot disappears. This activity helps you discover your blind spot, where your eye cannot detect light.
Draw a line through a picture and observe how your brain fills in the missing part. This activity demonstrates how your brain compensates for gaps in your vision, making the line appear continuous.
Watch two rectangles that seem to flash simultaneously. Move them slightly and notice how they flash out of sync. This activity shows how perception can be influenced by surrounding objects.
Look at flashing squares and try to read the sentence inside. Can you find the extra word? This activity highlights how your brain often skips over small mistakes to understand the whole sentence quickly.
Stare at the middle dot of a picture with changing colors. Notice how the color change seems to slow down or disappear when the image rotates. This activity explores how your brain makes quick assumptions based on learned patterns.
Your eyes help you see the world, but you can’t see this dot. No, seriously! If you close your left eye, stare at this crosshair with your right eye, and slowly move your head towards or away from the screen, the dot will disappear, revealing the exact location of your blind spot. The cells at the back of your eye transform light into signals that are sent to your brain, but they are missing right here because this is where nerves and blood vessels connect to the eye. So anything at that point in your vision, you can’t see—this is your blind spot.
If we add a line through the image and you try again, you’ll notice that your brain fills in information and makes you think the line is continuous instead of there being a hole in your vision. You also can’t see all 12 of these black dots at once for a similar reason. Go ahead and try! Chances are you’ll only see a fraction of them at once. The exact point your eye looks at is focused, but your peripheral vision isn’t great, so your brain often makes assumptions about what’s there. Because of the consistent gray line pattern, your brain assumes the rest of the image is just like that and misses the black dots until you look directly at them.
These two rectangles are flashing out of phase with each other. How about now? For most, the rectangles will now seem to be flashing at the same time, in phase, but they aren’t at all. Yet, if we move these shapes beside them just a few pixels, you’ll begin to see them out of phase again. The surrounding area has a direct impact on how you see and perceive things, even if the result isn’t correct.
Not convinced? Look at these flashing squares. Except, what you may not have seen is that the middle square isn’t flashing at all. If we remove the outer square, we see it for what it is—a solid color. Now try reading the sentence inside it. Did you catch the extra word? Your brain doesn’t always notice mistakes like these because it doesn’t affect your comprehension of the sentence, and your brain would prefer to act quickly rather than be perfectly accurate.
Try staring at the middle dot in this illusion. When the picture isn’t moving, the colors are clearly changing quickly. Yet when the image starts rotating, the color change either seems non-existent or much slower. Our eyes and brain have evolved to see, but our vision makes assumptions based on learning, memory, and expectation. All of these illusions take advantage of this adaptation.
It’s an advantage to have rapid information processing, so instead of taking in every bit of detail to be 100% accurate—which would cause a brain overload—your brain makes assumptions. This faster perception allows for quicker reflexes and faster conscious and unconscious decisions, an integral aspect of human nature. Much like this halo: if you stare at the center dot long enough, your brain will simply make it disappear. It makes an assumption that the information is unchanging or unimportant, and as a result, you can’t see it.
Love tricking your brain with illusions? We’ve put together a playlist of our favorite ones that you can watch by clicking the screen. Don’t forget to subscribe for more weekly fun science videos!
Blind Spot – A small area on the retina of the eye where the optic nerve connects, which lacks light-detecting cells and therefore cannot detect images. – Example sentence: In science class, we learned that everyone has a blind spot in their vision where the optic nerve connects to the eye.
Brain – The organ in the body that serves as the center of the nervous system, responsible for processing sensory information and controlling behavior. – Example sentence: The brain is like a supercomputer that helps us think, feel, and make decisions.
Perception – The process by which the brain interprets and organizes sensory information to understand the environment. – Example sentence: Our perception of color can change depending on the lighting and surroundings.
Vision – The ability to see; the sense that allows us to detect and interpret light to form images of the world around us. – Example sentence: Vision is crucial for many animals to find food and avoid predators.
Illusions – Visual or sensory experiences that appear different from reality, often tricking the brain into seeing something that isn’t there. – Example sentence: Optical illusions can make two lines of the same length appear different in size.
Color – The characteristic of visual perception described through categories like red, blue, and green, determined by the light’s wavelength. – Example sentence: The color of the sky changes from blue to orange during sunset due to the scattering of light.
Motion – The change in position of an object over time, which can be detected by the eyes and interpreted by the brain. – Example sentence: Our eyes can detect motion, allowing us to notice when something moves quickly across our field of vision.
Assumptions – Beliefs or ideas that are accepted as true without proof, often used by the brain to fill in gaps in information. – Example sentence: Our brain makes assumptions about what we see based on past experiences and knowledge.
Mistakes – Errors or incorrect actions or judgments, often resulting from misunderstandings or misinterpretations. – Example sentence: Scientists learn from their mistakes by analyzing what went wrong in their experiments.
Focus – The ability to concentrate attention on a specific task or object, often necessary for clear vision and understanding. – Example sentence: When studying, it’s important to focus on the material to understand it better.
