Internet users have been left baffled by a silent animation that you can ‘hear’.
The Gif shows a huge electricity pylon jumping over power lines like a skipping rope, causing the screen to ‘shake’ each time it lands.
Many users on Twitter, where the soundless Gif was first shared, have reported that they hear a ‘thudding’ noise each time the pylon lands.
The Gif shows an electricity pylon jumping over power lines like a skipping rope, causing the screen to ‘shake’ each time it lands. Many Twitter users have reported that they hear a thudding noise each time the pylon lands
Dr Lisa DeBruine, a psychologist at the University of Glasgow, posted the animation, asking: ‘Does anyone in visual perception know why you can hear this gif?’
She added a poll asking what people experienced when watching the Gif, with 75 per cent – around 15,000 people – claiming they heard ‘a thudding sound’.
Fourteen per cent of respondents, just under 3,000 in total, said they heard no sound, while under a thousand of the 20,000 polled said they heard ‘something else’.
The remainder of respondents, around 1,400, chose not to reveal whether they had heard anything.
In the responses to the strange post, Dr DeBruine suggested the effect is caused by the ear’s ‘acoustic reflex’.
Twitter user Mr Punkin wrote: ‘I think you can [hear] it because the visual expresses an implied wave, which your hearing system anticipates and prepares for so the potential sound doesn’t deafening you. The ear basically squints like an eye.’
Dr DeBruine tweeted in response: ‘That’s my perceptual experience, too. I can ‘squint’ my ears voluntarily and it’s a similar feeling.’
The acoustic reflex is an involuntary muscle contraction in the ear when we speak or hear loud noises.
Muscles pull tightly within the ‘middle ear’ to protect the delicate machinery of the inner ear from being damaged.
The reflex is mostly used against deeper, low-frequency sounds, such as the noise from a massive object colliding with the floor.
A poll asking what people experienced when watching the Gif found 75 per cent – around 15,000 respondents – heard ‘a thudding sound’
Dr DeBruine suggests that the dull thud people hear when watching the Gif is the sound of this reflex closing up part of our ear as we anticipate a loud noise.
Other experts suggest the effect is an illusion produced by our brains expecting a loud sound to accompany the sight of a big collision.
Dr Gustav Khun, a psychologist and human perception expert at Goldsmiths University in London, told MailOnline: ‘Perception is not an exact science and in most cases our brain makes an educated guess.
‘We use past experience and expectations to estimate what the world is truly like, base on the information our senses provide.
![It is expectation that is causing some people to hear the thuds, according to Professor Fiona Macpherson, an expert at the University of Glasgow (stock image)](https://i.dailymail.co.uk/i/pix/2017/12/04/14/27D2245E00000578-5143355-image-m-16_1512396529747.jpg)
It is expectation that is causing some people to hear the thuds, according to Professor Fiona Macpherson, an expert at the University of Glasgow (stock image)
‘This illusion works, because you have learnt that when larger objects fall to the ground, they result in a thumping sound.
‘Some viewers will actually hear the sound, simply because that it what they expect will happen.
Professor Fiona Macpherson, an expert at the University of Glasgow’s Illusion Index, told MailOnline: ‘It is expectation that is causing some people to hear the thuds.
‘In the GIF of the jumping pylon, there is a cross-modal expectation (that is, involving more than one sense, such as vision and hearing) effect taking place. What people see is affecting what they seem to hear.’