What's Really Happening When We See 'Stars' After Rubbing Our Eyes?

Photo illustration by Mental Floss. Images: iStock.
Photo illustration by Mental Floss. Images: iStock.

It's likely happened to you before: You start rubbing your eyes and almost immediately begin seeing colors, specks, and swirls from behind your closed lids. So what's happening when you see these 2001-esque "stars"? Do they only occur upon rubbing? Does everyone experience them?

Before we can get to what causes the lights, we need to understand a bit about how the eyes work. Angie Wen, a cornea surgeon at New York Eye and Ear Infirmary of Mount Sinai, tells Mental Floss that the retina—the innermost layer of the eye—consists of millions of cells, or photoreceptors. These cells, she says, "are responsible for receiving information from the outside world and converting them to electrical impulses that are transmitted to the brain by the optic nerve. Then, the brain interprets them as images representing the world around us."

However, what we see doesn't just stop there. Sometimes "we see light that actually comes from inside our eyes or from electric stimulation of the brain rather than from the outside world," Wen says. "These bursts of seemingly random intense and colorful lights are called phosphenes, and appear due to electrical discharges from the cells inside our eyes that are a normal part of cellular function."

People have been writing and theorizing about phosphenes for thousands of years. Greek philosophers thought the bursts of light were the result of fire inside our heads: "The eye obviously has fire within it, for when the eye is struck fire flashes out," wrote Alcmaeon of Croton (6th–5th century BCE), a philosopher and early neuroscientist, of the swirls and specks someone sees after getting a blow to the head. A century later, Plato—who believed that a "visual current" [PDF] streamed out of the eye—wrote that "Such fire as has the property, not of burning, but of yielding a gentle light they [the Gods] contrived should become the proper body of each day."

Plato's take was still the dominant one through the Middle Ages. Eventually, Newton (1642–1727) theorized a concept that's more in line with what's believed today about these strange sparkly visions: The phenomenon is due to light that's produced and observed when pressure and motion is placed on the eyes.

Eleonora Lad, an associate professor of ophthalmology at Duke University Medical Center who has a background in neuroscience, explains exactly why eye rubbing generates these visions: "Most vision researchers believe that phosphenes result from the normal activity of the visual system after stimulation of one of its parts from some stimulus other than light," including putting external pressure on the eyes. (Interestingly, due to retinal damage, blind people can't see phosphenes caused by pressure, but they can see them when their visual cortex is electrically stimulated. In hopes of turning this phenomenon into improved vision for the blind, scientists have developed a cortical visual prosthesis, implanted in the visual cortex, that generates patterns of phosphenes. The device has been approved by the FDA for clinical trial.)

As Alcmaeon rightly pointed out, there are causes for the bursts of light beyond just rubbing your eyes: Getting hit in the eye can produce this phenomenon—as can a sneeze, a surprisingly powerful event that tends to clamp our eyes shut, Wen says.

Receiving an MRI or EEG may also trigger it. MRIs, for example, produce a changing magnetic field which can stimulate the visual cortex, making a person see these flashing lights. When it comes to an EEG, depending on the brain stimulation frequency band (Hz) used, some patients experience the phenomenon when closing their eyes, which is believed to come from retinal stimulation during the process.

And the activity doesn't only happen on Earth; astronauts in space have also been known to experience them. As reported in 2006 in the journal Vision Research, "over 80 percent of astronauts serving in today's NASA or ESA (European Space Agency) programs have perceived phosphenes at least in some missions and often over several orbits." They're mainly attributed to interactions between the eye and cosmic ray particles in space, outside the Earth's protective magnetic field.

No matter the cause, the bursts of light are perfectly normal—but that doesn't mean you should engage in excessive eye rubbing. Wen says ophthalmologists advise against rubbing your eyes or applying vigorous pressure; according to Lad, too much rubbing may be damaging to the cornea and lens or "result in a loss of fatty tissue around the eyes, causing the eyes to look deep-set."

The Psychology Behind Kids' L.O.L. Surprise! Doll Obsession

Jack Taylor, Getty Images
Jack Taylor, Getty Images

Isaac Larian, the founder and CEO of toymaker MGA Entertainment, is an insomniac. Fortunately for him, that inability to sleep forced him to get up out of bed one night—a move that ended up being worth $4 billion.

Larian’s company is the architect of L.O.L. Surprise!, a line of dolls with a clever conceit. The product, which retails for about $10 to $20, is encased in a ball-shaped plastic shell and buried under layers of packaging, forcing children to tear through a gauntlet of wrapping before they’re able to see it. The inspiration came on that highly profitable sleepless night, which Larian spent watching unboxing videos on YouTube. It resulted in the first toy made for a generation wired for delayed gratification.

The dolls first went on sale in test markets at select Target stores in late 2016. MGA shipped out 500,000 of them, all of which sold out within two months. A Cabbage Patch Kid-esque frenzy came the following year. By late 2018, L.O.L. Surprise! (the acronym stands for the fancifully redundant Little Outrageous Little) had moved 800 million units, accounted for seven of the top 10 toys sold in the U.S., and was named Toy of the Year by the Toy Association. Videos of kids and adults unboxing them garner millions of views on YouTube, which is precisely where Larian knew his marketing would be most effective.

A woman holds a L.O.L. Surprise doll and packaging in her hand
Cindy Ord, Getty Images for MGA Entertainment

The dolls themselves are nothing revolutionary. Once freed from their plastic prisons, they stare at their owner with doe-eyed expressions. Some “tinkle,” while others change color in water. They can be dressed in accessories found in the balls or paired with tiny pets (which also must be "unboxed"). Larger bundles, like last year’s $89.99 L.O.L. Bigger Surprise! capsule, feature a plethora of items, each individually wrapped. It took a writer from The New York Times 59 minutes to uncover everything inside.

This methodical excavation is what makes L.O.L. Surprise! so appealing to its pint-sized target audience. Though MGA was advised that kids wouldn’t want to buy something they couldn’t see, Larian and his executives had an instinctual understanding of what child development experts already knew: Kids like looking forward to things.

Dr. Rachel Barr, director of Georgetown University’s Early Learning Project, told The Atlantic that unboxing videos tickle the part of a child’s brain that enjoys anticipation. By age 4 or 5, they have a concept of “the future,” or events that will unfold somewhere other than the present. However, Barr said, they’re also wary of being scared by an unforeseen outcome. In an unboxing video, they know the payoff will be positive and not, say, a live tarantula.

L.O.L. Surprise! is engineered to prolong that anticipatory joy, with kids peeling away wrapping like an onion for up to 20 minutes at a time. The effect is not entirely novel—baseball card collectors have been buying and unwrapping card packs without knowing exactly what’s inside for decades—but paired with social media, MGA was able to strike oil. The dolls now have 350 licensees making everything from bed sheets to apparel. Collectors—or their parents—can buy a $199.99 doll house. So-called “boy toys” are now lurking inside the wrappers, with one, the mohawk-sporting Punk Boi, causing a mild stir for being what MGA calls “anatomically correct.” His tiny plastic genital area facilitates a peeing function.

Whether L.O.L. Surprise! bucks conventional toy trends and continues its popularity beyond a handful of holiday seasons remains to be seen. Already, MGA is pushing alternative products like Poopsie Slime Surprise, a unicorn that can be fed glitter and poops a viscous green slime. An official unboxing video has been viewed 4.2 million times and counting.

More Than Half of Wild Coffee Species Could Go Extinct

iStock.com/Alfribeiro
iStock.com/Alfribeiro

Your morning cup of coffee is under threat. A study published today in Science Advances asserts that a majority of the world’s wild coffee species are at risk of extinction. The main two types we rely on for our caffeine fix—arabica and robusta beans—are both threatened by climate change and deforestation.

The team of UK-based researchers used Red List of Threatened Species criteria from the International Union for the Conservation of Nature to classify the risks facing the world’s 124 known species of wild coffee. About 60 percent of them—or 75 different species—face possible extinction in the coming decades. This represents “one of the highest levels recorded for a plant group,” researchers write in their paper.

Partly to blame are the severe droughts associated with climate change, as well as deforestation. Other threats include the spread of fungal pathogens and coffee wilt disease in Central and South America and Africa, respectively, as well as social and economic factors for growers.

“Considering threats from human encroachment and deforestation, some [coffee species] could be extinct in 10 to 20 years, particularly with the added influence of climate change," lead author Aaron P. Davis, of the Royal Botanic Gardens, Kew, tells CNN.

Davis’s previous research stressed that arabica, which is already listed as an endangered species, could be extinct within 60 years. Most of the coffee plants we rely on are farmed, but wild coffee is no less important. Some wild species are resistant to disease and have other useful genes that could be introduced to commercial crops. That way, the cultivated varieties might endure the effects of climate change better and stick around a little longer.

Consumers aren’t the only ones concerned, either. Coffee farming is an industry that supports about 100 million workers around the world. One way of conserving the plants is to store their seeds and genes, but Hanna Neuschwander, the director of communications for the industry group World Coffee Research, tells Mashable that these seed banks aren’t well established yet. For now, the focus is on preserving the plants themselves.

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