A bizarre clip of an audio illusion has gone viral on TikTok and it's left people questioning their own reality.
The clip in question is courtesy of TikToker Christian Rizea, a psychologist who shares tips, tricks and hacks relating to the human mind.
Text over the footage says 'you will only read what you hear' before showing two phrases – 'brainstorm' and 'green needle'.
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An unusual voice altered with sound effects then says one of these phrases, and the one you hear very much depends on which one you're looking at or thinking about while it's said.
So if you're looking at 'green needle', you'll hear 'green needle' and vice-versa.
Check it out for yourself:
Mind-blowing stuff, am I right? The internet seems to agree, with thousands of TikTokers taking to the comments section to share their thoughts.
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"But how!!!! I tested like 20 times," wrote one, while another said, "I listened to this like 20 times… there is no pattern... if I think of one it sounds like it."
"How does this work?" said a third, with a fourth adding, "This is scary..."
Others said they could hear a mixture of both, including this person who said: "I can do brain needle and green storm."
The video has gone massively viral since it was uploaded, amassing over 13.4 million views at the time of writing.
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Of course, this isn't the first time an audio illusion of this kind has done the rounds online – who else remembers the old Yanny vs Laurel debacle?
Similarly to this one, the internet was divided over whether the voice in the clip was saying 'Yanny' or 'Laurel', and it appears to be down to the same psychological trickery that we see with 'green needle' and 'brainstorm'.
Elaborating on why this is the case, Dr. Kevin Franck, director of audiology at Massachusetts Eye and Ear, previously told TIME magazine that it all comes down to the brain.
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“The fact that brains go in one way and some brains go in the other means that we’re all just wired a bit differently based on our experiences," he said.
“The brain is built to turn messy signals into meaning. It just will not give you ambiguity.”
Since the voices are heavily edited in these clips, when your brain is focusing on one phrase it'll fill in the blanks and tell you that's what you're hearing.
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The human mind, eh? It never ceases to amaze.
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