The latest optical illusion to have people shaking their heads requires, well, a literal shake of the head to see. 

The optical illusion made Internet rounds after a post on Twitter by nanotech engineer Dr Michelle Dickinson on January 9, 2019. 

“You can only see this optical illusion if you shake your head (I’m serious),” Dickinson wrote on Twitter.  

Really, try it!

Spoiler alert: Lurking within the drab box of vertical stripes is another Internet favorite – a cat.

After some searching, IFLScience found another example, albeit slightly less obvious as to who exactly it is.

“Someone is hidden,” wrote Akiyoshi Kitaoka, an experimental psychologist who both studies and makes visual illusions.

Here is another one.

Why does this happen? Well, it’s possible that the high contrast between the black and white lines is causing our perception to overlook the mild mid-tones in the white spaces. Our visual system often responds much stronger to sharp contrasts than to gradual changes. 

Optical illusions are a beautiful example of how our visual system is fallible. Although we like to think that what we see with our two eyes is reality, it is, in fact, a construct of incoming messages from our environment, sorted by our visual system for our brain to interpret. It is not a flawless, biological system. 

For further clarification on the illusion, IFLScience has reached out to neuroscientists for comment. Watch this space!

If you don’t feel like vigorously shaking your head in front of a co-worker, moving your eyes from side to side works too, as does going a tad cross-eyed. 

But really, it’s 2019 – shake away!