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Do People Really Walk in Circles When They’re Lost?

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It’s a reliable movie trope: Our heroes are lost in the woods, and in their valiant effort to make a beeline out of the forest or back to camp or civilization, they inevitably get turned around and wind up back at the same spot where they began.

When a science television show approached Jan Souman, a research scientist at the Max Planck Institute for Biological Cybernetics, with a viewer’s question about the phenomenon, Souman wasn't sure if people actually did accidentally circle back. When lost, he thought, people would probably veer left or right randomly, but not actually circle back.

To find out, he and his research group gathered nine volunteers and stuck six of them in a German forest and the other three in the Tunisian desert. All of them were instructed to walk as straight as possible in one direction for several hours while wearing GPS receivers so that the researchers could analyze their routes.

Course Correction

Souman found that all of them eventually veered off course, and more than half did end up circling back to cross their own paths without realizing it. There was an interesting twist, though. The circling only happened with the four of the forest walkers who made their journeys in overcast conditions and the one desert walker who walked on a night with no visible moon. Those who could see the sun or moon managed to travel in straighter lines and, when they did lose their way, moved as Souman had predicted, veering left and right while generally going in the same direction and not crossing back on their route.

In a second experiment, the researchers had 15 volunteers try to walk in a straight line for an hour while blindfolded. When they couldn't see at all, the walkers circled back sooner, more often, and in tighter arcs, sometimes making a circle about the size of a basketball court.

The two experiments cast doubt on an older idea that this kind of disorientation comes from biomechanical asymmetries—like a differences in length or strength between the left and right legs—that create small but consistent directional bias. That would cause a person to consistently veer off in the same direction, especially when the person is blindfolded and without visual cues to compete with the bias. But only three of the walkers had a tendency to veer in one direction, while the others varied wildly in their circling, with their paths looking like a child had scribbled on a piece of paper. Walking in circles, Souman and his team think, isn’t caused by some physical bias, but an uncertainty about where straight ahead lies that increases over time.

Visual Clues

For the walkers in the first experiment, visual cues appeared to be very important. Those who could see some external reference point—the sun, the moon, a hill in the far distance—could use it to recalibrate their sense of direction and maintain a relatively straight path. (Interestingly, Souman notes that the volunteers in the first experiment walked for several hours, during which the sun moved about 50 to 60 degrees; rather than following a correspondingly bent path, they were able to correct for this, even if subconsciously.)

The volunteers who walked when it was cloudy or dark or while they were blindfolded didn’t have this luxury and walked in circles. Without a reference point to maintain their course, these subjects had to rely on other cues, like sounds and information from the vestibular system, which aids in movement, balance and spatial orientation. Small random mistakes in the processing of these cues, Souman and team think, add up over time, especially when the senses are limited. Eventually, the internal compass fails and “random changes in the subjective sense of straight ahead” lead a person off the straight and narrow path and right back where they started from.

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Big Questions
What's the Difference Between Vanilla and French Vanilla Ice Cream?
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While you’re browsing the ice cream aisle, you may find yourself wondering, “What’s so French about French vanilla?” The name may sound a little fancier than just plain ol’ “vanilla,” but it has nothing to do with the origin of the vanilla itself. (Vanilla is a tropical plant that grows near the equator.)

The difference comes down to eggs, as The Kitchn explains. You may have already noticed that French vanilla ice cream tends to have a slightly yellow coloring, while plain vanilla ice cream is more white. That’s because the base of French vanilla ice cream has egg yolks added to it.

The eggs give French vanilla ice cream both a smoother consistency and that subtle yellow color. The taste is a little richer and a little more complex than a regular vanilla, which is made with just milk and cream and is sometimes called “Philadelphia-style vanilla” ice cream.

In an interview with NPR’s All Things Considered in 2010—when Baskin-Robbins decided to eliminate French Vanilla from its ice cream lineup—ice cream industry consultant Bruce Tharp noted that French vanilla ice cream may date back to at least colonial times, when Thomas Jefferson and George Washington both used ice cream recipes that included egg yolks.

Jefferson likely acquired his taste for ice cream during the time he spent in France, and served it to his White House guests several times. His family’s ice cream recipe—which calls for six egg yolks per quart of cream—seems to have originated with his French butler.

But everyone already knew to trust the French with their dairy products, right?

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

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Big Questions
How Many Rings Does Saturn Have?
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Of all the planets surrounded by rings, Saturn is the most famous. These planetary rings are massive enough that Galileo was able to see them using a simple telescope way back in 1610, though it wasn't until half a century later that another scientist was able to figure out what the "arms" Galileo saw actually were. NASA has since called them "the most recognized characteristic of any world in our solar system."

So how many rings does Saturn have, anyway? If you can see them from your backyard, there must be a lot, right?

Scientists don't know for sure exactly how many rings Saturn has. There are eight main, named ring groups that stretch across 175,000 miles, but there are far more than eight rings. These systems are named with letters of the alphabet, in order of their discovery. (Astronomers have known about ring groups A, B, and C since the 17th century, while others are newer discoveries. (The most recent was just discovered in 2009.)

The rings we can see in images of the planet—even high-resolution images—aren't single rings, per se, but are in fact comprised of thousands of smaller ringlets and can differ a lot in appearance, showing irregular ripples, kinks, and spokes. The chunky particles of ice that make up Saturn's rings vary in size from as small as a speck of dust to as large as a mountain.

While the gaps between Saturn's rings are small, the 26-mile-wide Keeler Gap is large enough to contain multiple moons, albeit very small ones. The largest ring system—the one discovered in 2009—starts 3.7 million miles away from Saturn itself and its material extends another 7.4 million miles out, though it's nearly invisible without the help of an infrared camera.

Researchers are still discovering new rings as well as new insights into the features of Saturn's already-known ring systems. In the early 1980s, NASA's Voyager missions took the first high-resolution images of Saturn and its rings, revealing previously unknown kinks in one of the narrower rings, known as the F ring. In 1997, NASA sent the Cassini orbiter to continue the space agency's study of the ringed planet, leading to the discovery of new rings, so faint that they remained unknown until Cassini's arrival in 2006. Before Cassini is sent to burn up in Saturn's atmosphere in September 2017, it's taking 22 dives through the space between the planet and its rings, bringing back new, up-close revelations about the ring system before the spacecraft dives to its death.

Though it's certainly possible to see Saturn's rings without any fancy equipment, using a low-end telescope at your house, that doesn't mean you always can. It depends on the way the planet is tilted; if you're looking at the rings edge-on, they may look like a flat line or, depending on the magnification, you might not be able to see them at all. However, 2017 happens to be a good year to see the sixth planet, so you're in luck.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

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