If you've ridden a crowded train recently, you may have noticed something unusual on other people's phones: small dots moving around the edges of their screens.
Those animated dots are part of a little-known iPhone accessibility feature called Vehicle Motion Cues, designed to help reduce motion sickness.
The setting places animated dots on the edges of the display that move in sync with the motion of the vehicle, using data from the phone's accelerometer.
Reviews are mixed, but some users have become enthusiastic supporters of the feature.
One New York commuter told the BBC that he likes it so much he keeps the dots activated all day, even when he is not travelling.
Why people get motion sickness
Motion sickness has long puzzled researchers.
One of the most widely accepted explanations is the sensory conflict theory, which suggests that the inner ear detects movement while the eyes perceive stationary surroundings, creating a mismatch in the brain.
However, Tom Stoffregen, Professor Emeritus at the University of Minnesota, disputes that theory.
According to Stoffregen, the issue may instead stem from the body's attempts to predict and control posture and movement. Motion sickness can occur when those predictions fail.
That may explain why passengers often become ill while drivers usually do not, because drivers are actively controlling the vehicle.
Either way, the confusion can lead to dizziness, disorientation and nausea.
Kristen Steenerson, Clinical Associate Professor at Stanford University and a specialist in the vestibular system, says the body may react this way because disorientation has historically been associated with poisoning.
When that happens, the body effectively decides that vomiting might be a useful response.
How the dots help
Steenerson says that providing the brain with visual clues about movement can reduce motion sickness.
The iPhone's moving dots appear to do exactly that.
"They give you a sense of how you are moving in space," she says.
Research into visual feedback suggests it can help alleviate symptoms.
A similar concept is used in anti-motion-sickness glasses containing liquid-filled rings that move as the wearer moves. Studies have indicated that such devices can be effective.
Steenerson, who experiences motion sickness herself, says the iPhone feature helps her to some degree.
"Everyone thinks there's something wrong with my screen. These dots are so cool," she says.
How to activate the feature
iPhone users can find the setting by opening:
Settings > Accessibility > Motion > Vehicle Motion Cues
The dots can be activated permanently or set to turn on automatically when the phone detects vehicle movement.
Users can also customise the size and colour of the dots.
Similar applications are available for Android devices, while reports suggest comparable functionality may eventually become available on Google's Pixel smartphones.
Not everyone is convinced
Some motion-sickness sufferers told the BBC that the feature made little difference.
Others describe it as transformative.
Zandie Brockett, a curator from New York City, says it has significantly improved her travel experience.
"It's been a game changer," she says.
She regularly recommends the feature to anyone who mentions getting carsick.
A similar endorsement came from Rory Carroll, editor-in-chief of automotive publication Alloy.
Despite spending much of his working life in vehicles, Carroll has suffered from motion sickness for years.
"It's solving a very specific problem that I've had my whole life. The dots really work," he says.
The screen-time dilemma
Supporters of Vehicle Motion Cues repeatedly highlight the same irony: the feature is only useful when motion sickness is caused by looking at a phone.
In other words, the benefit is that users can spend more time staring at their screens while travelling.
For some, that raises a broader question about modern technology.
As battery life improves, internet connectivity expands and devices become increasingly integrated into daily life, phones are reaching into spaces where people previously spent time disconnected.
Carroll acknowledges the contradiction.
"It is a bit of a bummer to have one less reason not to look at Instagram," he says.
For people who become nauseous while using their phones in cars, trains or buses, the animated dots may offer relief.
But there is another solution.
Put the phone away and enjoy the journey.
Source: BBC
