Study Finds Brains Literally "Sync Up" In Conversation

Study Finds Brains Literally "Sync Up" In Conversation

Good communication is a matter of getting "in sync" with others, as you've probably noticed when you've seen people match their steps perfectly as they walk, and imitate each other's gestures as they talk, and use each other's phrases and grammar. Last week, this paper reported  this kind of coordination in the most important place of all: When people converse, it reports, regions of their brains synchronize their activity. "Neural coupling," they argue, is a key part of communication.


Uri Hasson, Lauren Silbert and Greg Stephens recorded Silbert telling a 15-minute story while an MRI scanner recorded changes in activity levels in various regions of her brain. The researchers then played the recording to 11 volunteers while their brains were MRI-ed. As they listened, the paper reports, their brains' patterns of activity matched Silbert's.

The work is a nice departure from models that look for activity in "the brain," because, of course, communication doesn't take place in isolation. It also challenges the notion that listening and talking are neatly separated activities: "neural coupling" took place in both "comprehension" and "production" regions of the listeners' brains.

Especially interesting, as Michael Balter points out, were the regions in which the listeners went first: As they heard the story, their brains fired in a pattern that matched Silbert's, but hers came a moment later. They were, it seems, anticipating what she would say, priming themselves to hear what they expected. The better the match between Silbert's brain activity and these "predictive anticipatory responses" in a listener, the better the listener understood the story.

Thanks to some ingenious experiments by Sir Frederic Charles Bartlett in the 1930's, we know that listeners often "fill in" details of what they are hearing (and that their memories of the speaker don't distinguish between what they actually heard and what they supplied themselves). When students retold a folk tale he had given them to read, Bartlett found, they added some details (for instance, where the story read ``that Indian has been hit,'' some students recalled an Indian being killed, others an Indian being hit by an arrow). They also changed some unfamiliar facts (making the story's Indians "row" their canoe like proper English undergraduates). You can try it yourself: Read the story here, then re-tell it in a couple of days from memory, then compare what you've written or recorded to the original.

Yet these people felt sure that their memories of the story were accurate. They didn't notice the difference between what they had read and what they had supplied themselves. Why such confidence? Bartlett proposed that the mind understands the world by means of "schemas"—mental maps that relate actions and objects to each other. Once learned, the schema works rather like a form with blanks to be filled in. Once I know you're talking about Indians and canoes, I "fill in" arrows and moccasins even if you don't mention them (and I if you bring in samurai swords I might miss it, because those don't fit the schema).

Perhaps Hasson et al.'s paper, published in the Proceedings of the National Academy of Sciences, has touched on the physiological correlates of Bartlett's schemas. Perhaps, too, it has pointed to the physiological basis for the pleasure people take in synchronized activities—singing together in tune, marching together in time, doing the "wave." If "neural coupling" is essential to understanding others, then it would make sense that people would find it pleasurable and seek to create it.

Stephens, G., Silbert, L., & Hasson, U. (2010). Speaker-listener neural coupling underlies successful communication Proceedings of the National Academy of Sciences DOI: 10.1073/pnas.1008662107

A landslide is imminent and so is its tsunami

An open letter predicts that a massive wall of rock is about to plunge into Barry Arm Fjord in Alaska.

Image source: Christian Zimmerman/USGS/Big Think
Surprising Science
  • A remote area visited by tourists and cruises, and home to fishing villages, is about to be visited by a devastating tsunami.
  • A wall of rock exposed by a receding glacier is about crash into the waters below.
  • Glaciers hold such areas together — and when they're gone, bad stuff can be left behind.

The Barry Glacier gives its name to Alaska's Barry Arm Fjord, and a new open letter forecasts trouble ahead.

Thanks to global warming, the glacier has been retreating, so far removing two-thirds of its support for a steep mile-long slope, or scarp, containing perhaps 500 million cubic meters of material. (Think the Hoover Dam times several hundred.) The slope has been moving slowly since 1957, but scientists say it's become an avalanche waiting to happen, maybe within the next year, and likely within 20. When it does come crashing down into the fjord, it could set in motion a frightening tsunami overwhelming the fjord's normally peaceful waters .

"It could happen anytime, but the risk just goes way up as this glacier recedes," says hydrologist Anna Liljedahl of Woods Hole, one of the signatories to the letter.

The Barry Arm Fjord

Camping on the fjord's Black Sand Beach

Image source: Matt Zimmerman

The Barry Arm Fjord is a stretch of water between the Harriman Fjord and the Port Wills Fjord, located at the northwest corner of the well-known Prince William Sound. It's a beautiful area, home to a few hundred people supporting the local fishing industry, and it's also a popular destination for tourists — its Black Sand Beach is one of Alaska's most scenic — and cruise ships.

Not Alaska’s first watery rodeo, but likely the biggest

Image source: whrc.org

There have been at least two similar events in the state's recent history, though not on such a massive scale. On July 9, 1958, an earthquake nearby caused 40 million cubic yards of rock to suddenly slide 2,000 feet down into Lituya Bay, producing a tsunami whose peak waves reportedly reached 1,720 feet in height. By the time the wall of water reached the mouth of the bay, it was still 75 feet high. At Taan Fjord in 2015, a landslide caused a tsunami that crested at 600 feet. Both of these events thankfully occurred in sparsely populated areas, so few fatalities occurred.

The Barry Arm event will be larger than either of these by far.

"This is an enormous slope — the mass that could fail weighs over a billion tonnes," said geologist Dave Petley, speaking to Earther. "The internal structure of that rock mass, which will determine whether it collapses, is very complex. At the moment we don't know enough about it to be able to forecast its future behavior."

Outside of Alaska, on the west coast of Greenland, a landslide-produced tsunami towered 300 feet high, obliterating a fishing village in its path.

What the letter predicts for Barry Arm Fjord

Moving slowly at first...

Image source: whrc.org

"The effects would be especially severe near where the landslide enters the water at the head of Barry Arm. Additionally, areas of shallow water, or low-lying land near the shore, would be in danger even further from the source. A minor failure may not produce significant impacts beyond the inner parts of the fiord, while a complete failure could be destructive throughout Barry Arm, Harriman Fiord, and parts of Port Wells. Our initial results show complex impacts further from the landslide than Barry Arm, with over 30 foot waves in some distant bays, including Whittier."

The discovery of the impeding landslide began with an observation by the sister of geologist Hig Higman of Ground Truth, an organization in Seldovia, Alaska. Artist Valisa Higman was vacationing in the area and sent her brother some photos of worrying fractures she noticed in the slope, taken while she was on a boat cruising the fjord.

Higman confirmed his sister's hunch via available satellite imagery and, digging deeper, found that between 2009 and 2015 the slope had moved 600 feet downhill, leaving a prominent scar.

Ohio State's Chunli Dai unearthed a connection between the movement and the receding of the Barry Glacier. Comparison of the Barry Arm slope with other similar areas, combined with computer modeling of the possible resulting tsunamis, led to the publication of the group's letter.

While the full group of signatories from 14 organizations and institutions has only been working on the situation for a month, the implications were immediately clear. The signers include experts from Ohio State University, the University of Southern California, and the Anchorage and Fairbanks campuses of the University of Alaska.

Once informed of the open letter's contents, the Alaska's Department of Natural Resources immediately released a warning that "an increasingly likely landslide could generate a wave with devastating effects on fishermen and recreationalists."

How do you prepare for something like this?

Image source: whrc.org

The obvious question is what can be done to prepare for the landslide and tsunami? For one thing, there's more to understand about the upcoming event, and the researchers lay out their plan in the letter:

"To inform and refine hazard mitigation efforts, we would like to pursue several lines of investigation: Detect changes in the slope that might forewarn of a landslide, better understand what could trigger a landslide, and refine tsunami model projections. By mapping the landslide and nearby terrain, both above and below sea level, we can more accurately determine the basic physical dimensions of the landslide. This can be paired with GPS and seismic measurements made over time to see how the slope responds to changes in the glacier and to events like rainstorms and earthquakes. Field and satellite data can support near-real time hazard monitoring, while computer models of landslide and tsunami scenarios can help identify specific places that are most at risk."

In the letter, the authors reached out to those living in and visiting the area, asking, "What specific questions are most important to you?" and "What could be done to reduce the danger to people who want to visit or work in Barry Arm?" They also invited locals to let them know about any changes, including even small rock-falls and landslides.

Harvard study finds perfect blend of fruits and vegetables to lower risk of death

Eating veggies is good for you. Now we can stop debating how much we should eat.

Credit: Pixabay
Surprising Science
  • A massive new study confirms that five servings of fruit and veggies a day can lower the risk of death.
  • The maximum benefit is found at two servings of fruit and three of veggies—anything more offers no extra benefit according to the researchers.
  • Not all fruits and veggies are equal. Leafy greens are better for you than starchy corn and potatoes.
Keep reading Show less

Cephalopod aces 'marshmallow test' designed for eager children

The famous cognition test was reworked for cuttlefish. They did better than expected.

The common cuttlefish

Credit: Hans Hillewaert via Wikicommons
Surprising Science
  • Scientists recently ran the Stanford marshmallow experiment on cuttlefish and found they were pretty good at it.
  • The test subjects could wait up to two minutes for a better tasting treat.
  • The study suggests cuttlefish are smarter than you think but isn't the final word on how bright they are.
Keep reading Show less
13-8

If we do find alien life, what kind will it be?

Three lines of evidence point to the idea of complex, multicellular alien life being a wild goose chase. But are we clever enough to know?

Quantcast