You might remember back in 2017 when one particularly mind-blowing GIF went viral after baffling the Internet with its strange ability to evoke auditory hallucinations. The GIF itself was silent, and yet 70 percent of people reported being able to hear it. What on Earth was going on?
We're referring to this skip-jumping pylon, which, according to some, made a thudding sound every time it hit the ground:
Since then, some researchers have attempted to explain the strange phenomenon of "noisy GIFS". Notably, in 2018, a study published in the journal Cortex suggested that this totally bizarre occurrence – known as “visually-evoked auditory response” (vEAR) – affects roughly 20 percent of the population.
vEAR is a subcategory of synesthesia, a condition where the senses get muddled so that a person might "see" letters as specific colors or "smell" different genres of music. Traditionally, scientists estimate synaesthesia affects 4.4 percent of the population but the 2018 study suggests this common example of sensory "crosstalk" where people "hear" flashes and movements in silent videos could be far more widespread.
Researchers from City University in London recruited 4,128 volunteers to complete a survey testing their ability to "hear" gifs, such as a ballet dancer performing a pirouette. The respondents rated 24 silent video clips on a scale of one to five, with one being “no auditory sensation at all” and five being "vivid and definite auditory sensation”. They were also asked to provide demographic information and acknowledge any previous experience of vEAR.
A subset of the group (1,058 volunteers) was also asked to complete additional trait-related questions, such as “Do you suffer from tinnitus (ringing in the ears)?” and “Do you ever hear music in your head?”
"Some people hear what they see. Car indicator lights, flashing neon shop signs, and people's movements as they walk may all trigger an auditory sensation,” Dr Elliot Freeman, author of the study, said in a statement at the time.
"Ours is the first large-scale survey of this ability. We found that as many as 21 percent of people may experience forms of this phenomenon, which makes it considerably more prevalent than other synesthesias.”
The respondents were more likely to report "hearing" more realistic imagery (think: hammer hitting nails) as opposed to the more abstract imagery (swirling dots), though many described "hearing" both. The researchers found the synesthetes were also more likely to say they experience tinnitus and musical imagery, suggesting an underlying physiological cause to all three phenomena.
"We think that these sensations may sometimes reflect leakage of information from visual parts of the brain into areas that are more usually devoted to hearing. In extreme forms of this crosstalk, any abstract visual motion or flashing may be sufficient to trigger the sensation of hearing sounds," explained Freeman.
It's worth pointing out that the study was based on self-reporting and needs to be replicated, but it could offer interesting insights into the way people with synesthesia experience the world around them.
Another study, also authored by Freeman and published in 2020, attempted to elucidate the mechanisms underpinning this form of synesthesia. Its findings suggest there may be "two independent mechanisms underlying vEAR and its associated traits, based putatively on cortical disinhibition versus excitability."
But enough about hearing silent GIFS, can you see time?
An earlier version of this article was published in March 2018.