This instagram page posts videos of addicting optical illusions known as parallel view stereoscopic 3D videos. These videos feel like watching a 3D movie but without the red and blue goggles. It takes a bit of practice to train your eyes to view the illusion, but once you nail it, you won't want to stop watching these.
To make the illusion work, simply relax your eyes in the middle of the two images, as if you're looking through the screen. Once you see tree images, focus on the middle one and it becomes 3D. I found that the longer I stared at the middle image, the more clear and realistic the illusion became.
Keep in mind that It may take some practice to learn to do this. Don't cross your eyes, because this is for parallel viewing, not cross-eye viewing. If you're struggling, try placing your finger between your eyes and the screen to help guide your focus beyond it, then remove your finger. Have fun, and take frequent breaks to prevent eye strain.
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