If you trust all you see, you should think twice.
After all, countless researchers throughout history have proven that the brain uses “shortcuts” to make sense of the world (1). For instance, whenever you look at a clock, the first second will almost always seem longer than the seconds that come after. That’s because a part of that first second is a lie created by your brain to make up for the time it took to process the clock face.
Simply put, your brain and eyes cannot work fast enough to keep up with everything around you, at the exact time they happen.
“For that, our brain would need to be bigger than a building, and still then it wouldn’t be enough,” says Susana Marinez-Conde from the Barrow Neurological Institute, Arizona, to BBC (1).
Read on to experience some perceptual lapses for yourself – and find out how they work!
Optical Illusion: “16 Circles”
Take a look at the “16 Circles” optical illusion below. Published on Reddit in August 2017, this illusion has become notorious for proving that our eyes can be easily deceived – even when we are aware of the ruse (2).
Can you find all 16 circles?
If you can’t see the circles, here’s a tip: Focus on the vertical lines!
Still, the circles are difficult to spot, even after you know where they are. That’s because your brain interprets an image based on quick-and-easy “cues”. In this case, the powerful horizontal lines stand out as obvious “cues” – and your brain prefers to take those “cues” to understand the image as rows of rectangles.
The Ins-and-Outs of Optical Illusion
Here’s one explanation for optical illusions: Context (1)!
Certain cells in your brain responsible for picking up certain “cues” (e.g. horizontal lines), but not others (e.g. vertical lines)(3). The result? The combination of all the “cues” in the image – and the work of competing neurons – will determine what you see!
Consider classic examples of optical illusions below!
The Ponzo Illusion (4)
The top horizontal line may look longer than the one below it – but they are actually of the same length!
Here, your brain may take the two diagonal lines as “cues” that indicate distance and depth. As a result, the top line will seem “further” away from you (i.e. longer).
The Myers-Briggs Illusion (5)
These three lines are actually the same length – but do not appear that way at all.
Again, your brain interprets the “arrow tip” ends of each line as “cues” for depth. Can’t see why? Imagine folding a piece of paper. Now imagine that each line is the fold- and the “arrow tips” indicate how you are viewing the fold!
The Hering Illusion (6)
Here, the two red lines look bent – but are actually straight!
In other words, spoke-like lines may act as “cues” for depth and movement. As a result, you may think you’re “moving forward” into the picture, with the red lines bending accordingly as you “pass them by.”
The Necker Cube (7)
Imagine that this 2D diagram depicts a 3D cube. Is the cube facing up, to the right – or one facing down, to the left? That depends on the “cues” you decide to pick up!
More Optical Illusions
Looking for more fun optical illusions to test your eyes? Try the illusions and tricks in the video below (8):
So the next time you’re absolutely sure of what you’re seeing, just remember: Not everything may be as it appears!