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7 Teary Facts About the Science of Crying

We cry at sad movies, and at weddings. We cry when we stub our toes. Sometimes we cry to get what we want. Crying is one of the very first things we do in our lives, and sometimes is one of the last. Everybody cries, but how much do we really know about it? Read on to learn the science of why and how you cry, and what happens when you do.

1. CRYING REALLY DOES MAKE YOU FEEL BETTER.

Scientists videotaped 60 people as they watched sad movies. Of those 60, 28 cried during the screening, and 32 did not. The researchers found that directly after the movie, the people who had cried felt sadder than those who hadn’t. Ninety minutes later, however, those who had let their feelings out felt significantly better than their dry-eyed counterparts. More importantly, they also felt better than they did before watching the movie. 

2. YOU CAN KEEP ONIONS FROM MAKING YOU CRY, BUT IT'S A LITTLE AWKWARD.

A whole onion minds its own business and keeps its chemicals to itself. But cutting into an onion breaks cell walls and releases the compounds inside. When these compounds mix, they form a nasty gas called propanethiol S-oxide. The gas wafts upward toward your face, where it mixes with your tears to form sulfuric acid. Your eyes don’t want to have acid in them, so they make more tears to wash it out. But it doesn’t have to be this way. You can circumvent the whole process by wearing goggles as you chop your veggies. 

3. HAPPY TEARS AND SAD TEARS ARE PRETTY MUCH THE SAME.

Crying is one way for us to release strong emotions like grief, anger, and joy. All of these fall under the broad heading of “emotional arousal.” Such arousal takes a lot of work to maintain, and it’s in your body’s best interest to return to normal as soon as possible. Parts of your brain associated with strong emotion, like areas of the hypothalamus and basal ganglia, are connected to a part of the brainstem that regulates tear production.  

4. WANT TO DRIVE A HARD BARGAIN? START CRYING.

It’s a dirty trick, but it works. People who cry during negotiations are more likely to get their way. Context is important, though. Tearful bargaining is most effective under four distinct conditions: First, when the crier is in a position of inferiority or powerlessness; second, when the witness to the tears expects to see the crier in the future; third, when the witness sees the relationship with the crier as collaborative; and fourth, in situations where it was reasonable for the crier to be sad, not angry—that is, moments when there was nobody to blame. 

5. HUMANS ARE THE ONLY ANIMALS THAT CRY TEARS OF SADNESS.

“Crying” is a tricky term to describe. Many animals emit cries of fear, or alarm, or need, but these are noises only, with no tears. Non-human primates like chimpanzees have been known to cry out when separated from their mothers. Perhaps the most famous ape, Koko the gorilla, is said to have cried several times, including when she learned of the death of her first kitten and again upon hearing that Robin Williams had died. (Years before Williams' death, the comedian had spent the day with Koko, and the two bonded quickly.) In both situations, Koko reportedly let out sob-like sounds and signed the word “cry” to her keeper. Her emotional distress was clear, despite the absence of tears.

6. THE LUMP IN YOUR THROAT ISN’T REALLY A LUMP.

The body is a complex machine, with myriad systems running to keep you alive and breathing. Every stimulus, including intense emotion, triggers a bodily response. When you feel afraid or upset, your autonomic nervous system goes into high alert to manage whatever the threat might be. It speeds up your heart rate to make sure you’ve got enough blood in your arms and legs to flee. It stops your gut from digesting, since you might soon be making a break for it, and a pit stop would be inconvenient.

You’ll need more oxygen if you’re running, so the autonomic nervous system accelerates your breathing. It also enlarges the glottis, the opening in your throat that allows air to pass from your larynx to your lungs. This works well until you need to swallow, since swallowing involves closing the glottis. The tension between trying to hold the glottis open and trying to close it strains your throat muscles, which can feel like a lump in your throat. 

7. IT’S TOTALLY NORMAL TO CRY AFTER SEX.

It might seem counterintuitive to cry after coitus, but it’s really not that weird. Scientists surveyed 230 female college students and found that 46 percent of them had cried after sex at least once in their lives. Researchers call it postcoital dysphoria, or PCD. There are a few different theories about what causes it. Some scientists think it’s a natural response to the flood of hormones that accompanies sex. Others think that the vulnerability of sexual intimacy may allow people to open up and feel emotions they’ve been suppressing. Although the latest study focused on young women, PCD has been shown to affect both genders. Regardless of the cause, rest assured: It’s totally normal. 

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iStock // Ekaterina Minaeva
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Man Buys Two Metric Tons of LEGO Bricks; Sorts Them Via Machine Learning
Original image
iStock // Ekaterina Minaeva

Jacques Mattheij made a small, but awesome, mistake. He went on eBay one evening and bid on a bunch of bulk LEGO brick auctions, then went to sleep. Upon waking, he discovered that he was the high bidder on many, and was now the proud owner of two tons of LEGO bricks. (This is about 4400 pounds.) He wrote, "[L]esson 1: if you win almost all bids you are bidding too high."

Mattheij had noticed that bulk, unsorted bricks sell for something like €10/kilogram, whereas sets are roughly €40/kg and rare parts go for up to €100/kg. Much of the value of the bricks is in their sorting. If he could reduce the entropy of these bins of unsorted bricks, he could make a tidy profit. While many people do this work by hand, the problem is enormous—just the kind of challenge for a computer. Mattheij writes:

There are 38000+ shapes and there are 100+ possible shades of color (you can roughly tell how old someone is by asking them what lego colors they remember from their youth).

In the following months, Mattheij built a proof-of-concept sorting system using, of course, LEGO. He broke the problem down into a series of sub-problems (including "feeding LEGO reliably from a hopper is surprisingly hard," one of those facts of nature that will stymie even the best system design). After tinkering with the prototype at length, he expanded the system to a surprisingly complex system of conveyer belts (powered by a home treadmill), various pieces of cabinetry, and "copious quantities of crazy glue."

Here's a video showing the current system running at low speed:

The key part of the system was running the bricks past a camera paired with a computer running a neural net-based image classifier. That allows the computer (when sufficiently trained on brick images) to recognize bricks and thus categorize them by color, shape, or other parameters. Remember that as bricks pass by, they can be in any orientation, can be dirty, can even be stuck to other pieces. So having a flexible software system is key to recognizing—in a fraction of a second—what a given brick is, in order to sort it out. When a match is found, a jet of compressed air pops the piece off the conveyer belt and into a waiting bin.

After much experimentation, Mattheij rewrote the software (several times in fact) to accomplish a variety of basic tasks. At its core, the system takes images from a webcam and feeds them to a neural network to do the classification. Of course, the neural net needs to be "trained" by showing it lots of images, and telling it what those images represent. Mattheij's breakthrough was allowing the machine to effectively train itself, with guidance: Running pieces through allows the system to take its own photos, make a guess, and build on that guess. As long as Mattheij corrects the incorrect guesses, he ends up with a decent (and self-reinforcing) corpus of training data. As the machine continues running, it can rack up more training, allowing it to recognize a broad variety of pieces on the fly.

Here's another video, focusing on how the pieces move on conveyer belts (running at slow speed so puny humans can follow). You can also see the air jets in action:

In an email interview, Mattheij told Mental Floss that the system currently sorts LEGO bricks into more than 50 categories. It can also be run in a color-sorting mode to bin the parts across 12 color groups. (Thus at present you'd likely do a two-pass sort on the bricks: once for shape, then a separate pass for color.) He continues to refine the system, with a focus on making its recognition abilities faster. At some point down the line, he plans to make the software portion open source. You're on your own as far as building conveyer belts, bins, and so forth.

Check out Mattheij's writeup in two parts for more information. It starts with an overview of the story, followed up with a deep dive on the software. He's also tweeting about the project (among other things). And if you look around a bit, you'll find bulk LEGO brick auctions online—it's definitely a thing!

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iStock
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Why Your iPhone Doesn't Always Show You the 'Decline Call' Button
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iStock

When you get an incoming call to your iPhone, the options that light up your screen aren't always the same. Sometimes you have the option to decline a call, and sometimes you only see a slider that allows you to answer, without an option to send the caller straight to voicemail. Why the difference?

A while back, Business Insider tracked down the answer to this conundrum of modern communication, and the answer turns out to be fairly simple.

If you get a call while your phone is locked, you’ll see the "slide to answer" button. In order to decline the call, you have to double-tap the power button on the top of the phone.

If your phone is unlocked, however, the screen that appears during an incoming call is different. You’ll see the two buttons, "accept" or "decline."

Either way, you get the options to set a reminder to call that person back or to immediately send them a text message. ("Dad, stop calling me at work, it’s 9 a.m.!")

[h/t Business Insider]

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