Optical illusion: can you tell if these lines are straight or curved?

Optical illusion is a resource used in images that confuse us by giving rise to multiple interpretations, depending on the point of view. They end up being perceived in a way by the system visual and the other by the brain. In Herring, Worth & Packard's 1999 illustration, red and blue lines will intrigue you.

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Can you identify if they are really curved or straight?

test your skills

Generally we come across three types of optical illusions. Are they:

• Literal: occurs when the brain fills in the details of the image with information that does not exist, making more than one drawing, for example, visible;
• Cognitive: happen when the image distorts the perception of the world that is known by the observer;
• physiological: these are illusions that excessively stimulate the brain through colors, shapes and brightness, deceiving the visual system.

The following illusion uses exactly colors and shapes to mess with our perception. The objective is simple: you must say if the red lines are straight or curved. Is it possible?

tricking the brain

And there? Were you able to identify if they are straight or not? If you answered “yes, they are straight lines”, congratulations, because you got it right! The blue lines cause a delay in perception because they are blurred, not allowing to fix a point, making the brain understand that they are moving.

The illustrators explain that, although the red lines are straight and parallel, the way the blue ones are positioned towards the center of the image ends up changing perception. The mind understands that if the blue lines are moving, then the red line is also moving, giving the impression that it is curved. In other words, it's all because of the image's background playing with different colors and shapes.

In the following image, the color of the background lines has been removed, highlighting only the red, making it possible to see how the lines are straight and parallel.