To the delight of a great many cognitive scientists, perceptual illusions have undeniably been in vogue thanks to a whole wardrobe of controversial garments including dresses (mostly, yes, the dress), flip-flops, jackets, and sneakers. What these all have in common is that the individual percept seems to be highly subjective, ultimately influenced—if not determined—by the idiosyncratic life experience of the observer. The latest such craze to hit the internet via Twitter comes to us in the form of a meme—rope-jumping pylons. This one has actually been around for quite a while but only achieved viral traction recently, I believe due to the fact that @lisadebruine popularized @IamHappyToast’s original creation with the question, “Does anyone in visual perception know why you can hear this gif?”
I must confess—when I first saw this a long time ago, I found it cute, but the thought of it producing any sort of noise did not enter my mind. But now it does … make a sound. Conversely, my wife can’t hear anything, but she does feel the vibrations from the jumping pylon. Many Slate staffers, upon seeing the GIF, agreed that they “felt it more than they heard it.” Slate’s editor-in-chief Julia Turner put it aptly when she said she “experienced something that felt, for lack of a better description, like a clenched brain response that was almost like a sound.” Some realized they could hear it if they thought about it right—and if the thumping gets too loud, closing your eyes fixes that.
This suggests that at least part of the phenomenon might be due to suggestibility—how likely an individual is to accept something when there are gaps in the information. But at the risk of disappointing the asker of the original question, we do not know why we can hear this GIF, let alone why some people can and others cannot. But this is not even the first meme that, by the power of suggestion, seems to assert control over our inner voice/ear—this one does, too.
There are probably a great many phenomena at play here: In addition to suggestibility, at a minimum, we are talking about auditory imagery, synesthesia, and cross-modal perception. None of these are particularly well understood on their own, let alone differentially, but we do know that the ability of people to engage in each differs between individuals.
Mental imagery is the ability to imagine perceptual qualities that are not objectively there, such as sights and sounds, and it engages the same brain regions involved in perceiving modalities. We live in an uncertain and hostile world, so the brain uses all information at its disposal in order to reduce uncertainty and increase the odds of survival. One such possibility comes in the form of cross-modal perception—if information in one modality is more certain than in another, this has been known to induce changes in how we perceive events in the other modality. For instance, a subtle “click” at the right time can dramatically shift our perception of whether two balls bounce away from each other or slide over each other—try this without sound first, to see what I mean.
Finally, synesthesia is the tendency of some individuals to have a perceptual experience that is evoked by a stimulus that generally does not lead to such an experience, such as “feeling” a sound or “tasting” a word. The most common form of this—having letters or numbers associated with specific colors—is actually not that uncommon. We do not know why some people are synesthetes and others are not. It might be that some people simply have less neural inhibition in general, although the specificity of synesthetic experiences and the fact that it could be shown that the links between letters and colors map to those of a popular colored letter-magnet set suggest learned associations are at play.
Anyway, even though we have some ideas, we do not know exactly why some people hear the rope-jumping pylons and others do not, but we do know that this kind of thing is not unusual—and by that I mean both induced cross-modal percepts and humans not fully understanding why a scientific phenomenon is happening, particularly between individuals, is not unusual. This particular phenomenon will be hard to study covertly: How would one investigate whether study participants hear something without asking them? Doing so might plant the very idea that there might be a sound to be heard in their head in the first place.
At any rate, if you have a couple of minutes and want to help us understand, click here.