Optical illusions are confusing and unnecessary but we also can’t look away.

They are guaranteed to hurt your brain.

But this one also hurts… your neck.

Engineer Dr Michelle Dickinson has shared this optical illusion to Twitter and people are losing it.

You can only see this optical illusion if you shake your head (I’m serious) ???? pic.twitter.com/WhtZ1b0r4t

— Dr Michelle Dickinson (@medickinson) January 10, 2019

In the tweet she explained that in order to see the illusion, you have to shake your head.

At first glance, the image is simple black and white stripes.

While it worked immediately for some people, others had a bit of… trouble.

I don’t see it. I’m shaking my phone but all I see is bars on my desktop monitor. ????

— EconRob (@econ_rob) January 11, 2019

It looks the same whatever I do.

— Mr Scott (@MrScottMaths) January 10, 2019

I have more luck moving the picture back and forth, though I grant you I’m also following it with my head. Is that interesting or banal? I’m assuming the latter…

— Nick Harkaway (@Harkaway) January 10, 2019

Other, superior beings, could see the (spoiler) animal straight away…withoutshaking their head.

I see it without shaking my head. But if I cover one eye it disappears!

— Lee Mauger (@kiwidonkey) January 10, 2019

I easily see a cat without shaking my head, nor the smartphone

— Boris MegreLaw (@PourqoisPas) January 13, 2019

I see a black cat without shaking my head :)

— Leo Rietdijk (@DieterLeo) January 11, 2019

I don’t have to shake anything at all to see it…

— Bart VdB ???????????? (@bart_eco) January 11, 2019

I saw it too without any effort, without a specific skill: am I different?

— Giuseppe Gelao (@Giuseppe_Gelao) January 15, 2019

Regardless of the outcome, there are a lot of people lookingverysilly while they look at their phones right now.

No necks were injured in the making of this post.