The McGurk Effect (Or, Brains are Weird)

YouTube // BBC
YouTube // BBC

The McGurk effect is mind-blowing. It involves showing a person's lips making the shape of one sound—like "bah"—while the audio is actually the person saying "fah." What's interesting is that your brain changes what you "hear" based on what you see. It's "bah" all the way through, but when we see "bah" our minds transform "bah" into "fah."

The effect is named for researcher Harry McGurk, who published a 1976 paper with John MacDonald entitled "Hearing lips and seeing voices." McGurk and MacDonald described how speech perception isn't just about sound—it's also affected by vision, and the integration of the two.

What's most interesting about the McGurk effect is that, even when the viewer knows what's happening, it still works. In other words, even thought I know it's an illusion, my brain can't seem to turn off the effect. Note: Some people are not susceptible to the effect; please leave a comment either way!

Here's a nice BBC segment illustrating the effect (jump to 0:30 if you just want to see the effect in action):

More Than 350 Franklin Expedition Artifacts Retrieved from Shipwreck of HMS Erebus

Drone image above the HMS Erebus shipwreck.
Drone image above the HMS Erebus shipwreck.
Parks Canada's Underwater Archaeology Team

From a shallow Arctic gulf, a treasure trove of objects from the HMS Erebus shipwreck has been brought to the surface for the first time in more than 170 years. The items could offer new clues about the doomed Franklin expedition, which left England in 1845 to search for the Northwest Passage. All 129 people perished from still-uncertain causes—a mystery that was fictionalized in the AMC series The Terror in 2018.

Marc-André Bernier, head of underwater archaeology at Parks Canada, said in a teleconference from Ottawa that this year’s research season was the most successful since the discovery of the HMS Erebus shipwreck in 2014. Parks Canada divers and Inuit located the HMS Terror, the second ship of the Franklin expedition, in 2016.

Parks Canada diver at HMS Erebus shipwreck
A Parks Canada diver retrieves a glass decanter at the HMS Erebus shipwreck.
Parks Canada's Underwater Archaeology Team

From mid-August to mid-September, 2019, the Parks Canada and Inuit research team began systematically excavating the large and complex shipwreck. “We focused on areas that had not been disturbed since the ship had sunk,” Bernier said. “Right now, our focus is the cabins of the officers, and we’re working our way toward the higher officers. That’s where we think we have a better chance of finding more clues to what happened to the expedition, which is one of the major objectives.”

Over a total of 93 dives this year, archaeologists concentrated on three crew members’ cabins on the port side amidships: one belonging to the third lieutenant, one for the steward, and one likely for the ice master. In drawers underneath the third lieutenant’s bed, they discovered a tin box with a pair of the officer’s epaulets in “pristine condition,” Bernier said. They may have belonged to James Walter Fairholme, one of the three lieutenants on the Erebus.

HMS Erebus shipwreck epaulets
A pair of epaulets, which may have belonged to third lieutenant James Walter Fairholme, was found at the HMS Erebus shipwreck.
Parks Canada's Underwater Archaeology Team

In the steward’s pantry, where items used to serve the captain were stored, divers carefully brushed away sediment to reveal dozens of plates, bowls, dish warmers, strainers, and more— about 50 serving pieces total. Bernier said some of the most exciting finds were personal objects that could be linked to individuals, such as a lead stamp with the inscription “Ed. Hoar,” for Edmund Hoar, the 23-year-old captain’s steward. They also found a piece of red sealing wax with a fingerprint of its last user.

Dishes at HMS Erebus shipwreck
Divers found dishes in the steward's pantry at the HMS Erebus shipwreck.
Parks Canada's Underwater Archaeology Team

Other intriguing items brought to the surface include a glass decanter, found in the officers’ mess area on the lower deck, which may have held brandy or port; a high-quality hairbrush with a few human hairs still in the bristles; and a cedar-wood pencil case. All of the artifacts are jointly owned by the Government of Canada and Inuit.

Hairbrush from HMS Erebus shipwreck
A hairbrush discovered at the HMS Erebus shipwreck still had a few human hairs in the bristles.
Parks Canada's Underwater Archaeology Team

The extensive recovery was made possible by a new research barge, which was moored over the shipwreck and provided hyperbaric chambers and hot-water suits. While wearing the suits, divers were able to stay in the frigid waters for about 90 minutes at a time; they spent over 100 hours examining the wreck this year.

The HMS Erebus’s size and excellent state of preservation mean there’s much more to discover, Bernier said. The Erebus is 108 feet long, and though the upper deck has collapsed, there are 20 cabins on the main deck. They’ve examined only three so far. “There are tens of thousands of artifacts still there,” Bernier tells Mental Floss. “We’re going to be very focused and save what needs to be saved, and go to places [in the wreck] where there are good chances of finding the most information that is valuable for the site.”

Parks Canada and Inuit archaeologists
Parks Canada and Inuit archaeologists set up instruments near the HMS Erebus shipwreck.
Parks Canada's Underwater Archaeology Team

As with the findings from previous research seasons, many questions about the shocking demise of the Franklin expedition remain unanswered. How and when did the HMS Erebus sink after both ships were abandoned in spring 1848, having been trapped in ice since September 1846? Which officers and crew were among the 24 men who had died by that time, and why so many?

Bernier tells Mental Floss there’s even a new mystery to solve. Near Edmund Hoar’s items, divers found another artifact that also bore the name of a crew member—mate Frederick Hornby. “Originally, when the ships set sail, he was not on Erebus, he was on Terror,” Bernier says. “So this object jumped ship at one point. How did that happen? Was Hornby transferred to Erebus; did they abandon one ship and put everybody on the other one? Was it something somebody recovered after he died? Was it given to somebody? With one object, we can start to see [new] questions. Hopefully, by piecing all of this together, we can actually start pushing the narrative of the story in some interesting direction.”

The Reason Our Teeth Are So Sensitive to Pain

This woman's tooth pain is actually helping her avoid further damage.
This woman's tooth pain is actually helping her avoid further damage.
champja/iStock via Getty Images

On a good day, your teeth can chew through tough steak and split hard candy into pieces without you feeling a thing. But sometimes, something as simple as slurping a frosty milkshake can send a shock through your tooth that feels even more painful than stubbing your toe.

According to Live Science, that sensitivity is a defense mechanism we’ve developed to protect damaged teeth from further injury.

“If you eat something too hot or chew something too cold, or if the tooth is worn down enough where the underlying tissue underneath is exposed, all of those things cause pain,” Julius Manz, American Dental Association spokesperson and director of the San Juan College dental hygiene program, told Live Science. “And then the pain causes the person not to use that tooth to try to protect it a little bit more.”

Teeth are made of three layers: enamel on the outside, pulp on the inside, and dentin between the two. Pulp, which contains blood vessels and nerves, is the layer that actually feels pain—but that doesn’t mean the other two layers aren’t involved. When your enamel (which isn’t alive and can’t feel anything at all) is worn down, it exposes the dentin, a tissue that will then allow especially hot or cold substances to stimulate the nerves in the pulp. Pulp can’t sense temperature, so it interprets just about every stimulus as pain.

If you do have a toothache, however, pulp might not be the (only) culprit. The periodontal ligament, which connects teeth to the jawbone, can also feel pain. As Manz explains, that sore feeling people sometimes get because of an orthodontic treatment like braces is usually coming from the periodontal ligament rather than the pulp.

To help you avoid tooth pain in the first place, here are seven tips for healthier teeth.

[h/t Live Science]

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