Optical illusion of fish or mermaid goes viral - but people say they see something different

An optical illusion supposedly showing a fish or mermaid has gone viral on social media - but some people say they see something different entirely.

The image, posted on Twitter, is captioned: "If you're right-brained you'll see a fish. If you're left-brained you'll see a mermaid."

But many say they see neither.

Rather, people on platform are spotting an array of other animals instead, such as a donkey, seal, kangaroo or aardvark, MyLondon reported.

One person wrote: "Well I see either a donkey or a seal with it's tail the air. Dunno what that says about my brain."

Another commented: "I see a seal and a donkey. The only thing I don’t see is a mermaid or a fish"

Even some celebrities got involved.

JK Rowling said: "It's a donkey, though".

Piers Morgan added: "Agreed - a donkey"

Trawling through all the comments, it appears no one seems to see a mermaid or fish.

The post claimed that you are right-brained - which means you are more creative or artistic - if you see a fish, and left-brained - or more analytical and methodical - if you see a mermaid.

But what does that mean for the rest of us who see neither?

The whole affair is somewhat reminiscent of The Dress phenomenon from a few years ago, or more recently, the hidden numbers in a hypnotic optical illusion.

If you don't know what this is referring to, the brief overview is that the picture of a striped dress went viral online in 2015, with some people saying they saw a blue and black dress, while others were adamant it was white and gold.

It revealed the differences in human colour perception and has since been the subject of investigations into neuroscience and vision science.

Scientific papers have even been produced off the back of it.

What do you see? Let us know in the comments.