Optical illusions are an entertaining way of letting our brains get tricked.

One viral illusion shared on Twitter in particular has everyone perplexed, as they try to read between the lines (quite literally).

All the lines are straight, Twitter user @ih8rts wrote in the caption alongside the image of a grid with green lines and a static-looking background.

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But what has left people surprised, is the fact that the lines are straight despite us perceiving them to be curved when looking at the image.

Since sharing the interesting image, the optical illusion has received 306,000 likes - so that's a lot of eyes attempting to understand what is going on.

It's fair to say this illusion was hard for people to wrap their heads around...

So what causes us to think the lines are curved when they are not?

One person shared their theory and wrote: Some of the boxes are different shades of grey and it throws the illusion of curved lines

Another person also echoed this point and included some annotated diagrams to highlight the curved lines (in purple) that everyone sees as a result of the grey boxes.

The lines ur seeing r just uneven patches of light grey boxes - when ur not focused on them ur brain catches the pattern but when u look directly at them it’s less obvious cuz they arent actually clearly defined lines the side-by-side highlights some grey patches idk if it helps, they wrote.

Optical illusion solved...

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