First we had that dress, then came the colour-changing flip-flops. Today, the internet is divided over a new type of sensorial enigma in the form of a GIF, which may or may not make a noise (hint: it doesn't).
Originally created by HappyToast, the GIF, which sees an electricity pylon skipping with its friends, was shared via Twitter by Lisa DeBruine who asked: "Does anyone in visual perception know why you can hear this gif?"
Convinced that she could hear a 'thudding' noise every time the structure hit the ground, she went on to conduct a survey to find out what everyone else thought. And of course, the internet reacted with its usual degree of hysteria. Luckily, as with all the other internet-hyped 'mysteries', the response is quite simple.
As The Verge explains, the 'thudding' phenomenon is due to something called synesthesia, which describes the process when our senses get a bit cross-wired and apply multiple sensory reactions – like seeing and hearing – to a single stimulus, when it should actually only trigger one.
It's the same principle that means that, in very rare cases, people can sometimes 'hear' colours or visualise what certain sounds look like. But beyond these exceptional cases, we're all affected by synesthesia throughout each day of our lives.
Our brains have therefore learned to associate certain movements and materials with sounds. For example, if we see a glass bottle fall, we'll brace ourselves to hear the sound of it smashing. And that's probably why so many people are sure they can hear the noiseless GIF – because their brains have been wired to anticipate the noise.
As we see the ground 'shake', we expect the rumbling noise that comes with it, a reaction which University of London researcher Christopher Fassnidge refers to as a "visually-evoked auditory response."
While movement-hearing synesthesia has not been well-researched, it is thought to affect around 20% of the population – a figure that should be reflected in the results of the survey.
So there you have it, there is a perfectly reasonable explanation and there's no need to have another meltdown à la dress. If you enjoyed that sensory experience, Reddit has dedicated a whole section to the same kind of GIF – as long as you promise not to make a big deal out of it.