Why Broken Escalators Throw Off Our Balance

The feeling of a "phantom escalator" has a scientific explanation.
(vargklo/flickr)

The escalators on the D.C. Metro are very tall and they are always breaking. This sucks a little if you are just lazy like me, it sucks a lot if you’re on crutches or you have a suitcase. But even when you know the escalator is broken, and expect it not to be moving, for many people, there’s still a moment of disorientation when you step on and start climbing, a weird imbalance that doesn’t happen with equally motionless stairs. But a broken escalator is stairs. Hence the mystery.

Luckily, chances are that if you’ve stopped to wonder about something before, somewhere, a researcher has likely done the same. In this case it was R.F. Reynolds and A.M. Bronstein, who in 2003 published a study called “The Broken Escalator Phenomenon,” which they defined as “an odd sensation of imbalance, despite full awareness that the escalator is not going to move.”

To recreate the feeling in an experimental setting, the researchers used a mobile sled, which participants stepped onto from a stationary platform. First they stepped onto the sled 10 times while it wasn’t moving, then stepped onto it 20 times while it was in motion. Then the researchers stopped the sled, clearly told the participants it wouldn’t be moving, and had them walk onto it again. Even though they knew the sled wasn’t moving, they still walked onto it too fast, swaying their torsos forward. “There was a forward sway of the trunk by about 14.9 centimeters above that of the final resting stance position,” the study reads. Many of the subjects said they were surprised by the feeling, and some of them compared it to walking onto a broken escalator.

“Adapting our gait to cope with a predictably moving surface is a common facet of life in modern cities, on escalators and moving walkways,” the study says. And it appears from this study that the change, be it walking faster or leaning forward, that we make to smoothly transition onto a moving platform, is so ingrained that we can’t fully correct for it, even when we know the escalator is broken. We correct a little—the effect was less pronounced when participants knew the sled would be stationary, as opposed to the couple of times the researchers surprised them with its lack of motion—but not enough.

A similar effect has been shown in people who cautiously step on a previously-slippery surface, even when they know it’s no longer slick. A follow-up study, published in PLOS One in 2009 indicated that it’s the “highly habituated visual input”—we’re used to seeing escalators move—that creates the feeling of a “phantom” escalator.

Previous research, according to the 2003 study, has suggested that “the motor system cannot readily switch between two newly learned behaviors, even when the change in context is predictable.” This happens even if you consciously try to suppress the effect with the incredible power of your mind. Try though we might to control our bodies, some part of them will always remain free, wild, tripping on escalators.

As my colleague Nolan Feeney pointed out, this seems like the sort of phenomenon that should have a long German word to describe it, so let’s make one. Google Translate tells me “broken” is “gebrochen” and “escalator” is “Rolltreppe.” So, gebrochenrolltreppe it is.

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Julie Beck is a senior associate editor at The Atlantic, where she oversees the Health Channel.

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