You might remember one particularly mind-blowing GIF that went viral last year after baffling the Internet with its strange ability to evoke auditory hallucinations. The skip jumping pylon made a thudding sound every time it hits the ground – at least, that’s what 70 percent of people will tell you. In reality, the clip was completely silent.
A new study published in the journal Cortex suggests that this totally bizarre phenomenon – 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 this new 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,” Elliot Freeman, author of the study and a Senior Lecturer in Psychology at City University, said in a statement.
"Ours is the first large-scale survey of this ability. We found that as many as 21% 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 it would be interesting to see if the results can be replicated in future studies, but it could offer interesting insights into the way people with synesthesia experience the world around us.
In the meantime, can you hear any of these "loud" gifs?