AILSA CHANG, HOST:
It’s time now for our science news roundup from Short Wave, NPR’s science podcast. I’m joined by the show’s two hosts, Regina Barber and Emily Kwong. Hey to both of you.
REGINA BARBER, BYLINE: Hey.
EMILY KWONG, BYLINE: Hey, Ailsa.
CHANG: Hey. OK, so you have brought us three science stories, as you always do – stories that caught your attention this week. What are they?
KWONG: We have for you how spiders add decorations to their webs.
CHANG: Ooh.
BARBER: Plus, why more pixels on your HDTV might not make a difference.
KWONG: And how different kinds of stories change your brain.
CHANG: Ooh. OK, let’s take spider webs first, just in time for Halloween.
KWONG: Yes, I want to talk about orb webs. That’s the spider web that looks like a wheel with concentric circles of silk on the spokes.
CHANG: Yes…
KWONG: Yeah…
CHANG: …I’ve seen these. They’re so beautiful.
KWONG: …They’re so pretty, yeah. And sometimes orb webs have these additional bits of silk called stabilimenta – stabilimenta – which look like a zigzag of threads or a flattened disc decoration.
CHANG: Oh, I think I have seen these right before I’ve walked into a spider web with my face.
(LAUGHTER)
CHANG: Why are spiders decorating like that?
BARBER: Yeah, no one knows for sure. The stabilimenta do reflect a wide range of light, so there’s an idea that they might help attract prey or deter predators, but it’s a big debate among silk scientists.
GABRIELE GRECO: Discussing about stabilimenta for silk scientists is like picking up an easy fight.
CHANG: Even that word stabilimenta sounds so beautiful.
(LAUGHTER)
KWONG: This is Gabriele Greco. He wanted to throw another idea into the debate ring. He’s a physicist and lead author of a new paper in the journal PLOS One, and he wondered if the stabilimenta actually help spiders locate their prey.
CHANG: I mean, that would be ingenious. Why would they need help, though?
KWONG: Well, spiders, many of them have low vision. They can’t look across the web and see their prey. Instead, they rely on the web’s vibrations to sense dinner.
BARBER: So when a fly hits the web, the impact sends out waves in all directions, like a string of a guitar being strummed, and that lets the spider know where their dinner has landed. And Gabriele wanted to know if the decorations helped in any way with wave propagation.
CHANG: That is fascinating. And how did he go about testing that?
BARBER: His team ran simulations – like, modeled web vibrations with a computer – and found that when vibrations moved perpendicular to the spokes of the simulated web, the stabilimenta didn’t make a difference, but when the vibrations move parallel to the spiral threads of the web, the decorations did help. So the presence of the stabilimenta allowed the wave to travel farther.
CHANG: So they finally settled the debate.
KWONG: No, they actually complicated the debate. Gabriele recognizes his study has limits. It’s just a simulation, and real webs are much more complex. Outside researchers, including Shichang Zhang, an ecologist at Hubei University, noted the study lacks behavioral data from real spiders. So to figure out if there’s some kind of mechanical purpose for the stabilimenta, Gabriele plans to do more research, both in the lab and in the field.
CHANG: So cool. OK, next up – tell me about the study about pixels on my TV.
BARBER: Yeah. So a team from the University of…
CHANG: Did I buy the wrong TV?
BARBER: We’ll get there. Don’t worry.
CHANG: (Laughter).
BARBER: So a team from the University of Cambridge in the U.K. decided to ask the question, like, how many pixels on your high-definition TV, or really any display, is too many? So pixels being that smallest unit of a digital image, that tiny colorful square.
CHANG: Yeah.
KWONG: So researchers had 18 people look at images on an adjustable display to see if they could distinguish between different resolutions or a level of detail. And what they determined is that there is a limit.
CHANG: A limit? Wait, what does that mean? Like, are certain fancy TVs with a ton of pixels just not worth it?
BARBER: So it depends. So keep in mind, there are so many factors that matter here. So we talked to Maliha Ashraf about it, and she’s a human vision researcher and lead author of the study published in the journal Nature Communications.
MALIHA ASHRAF: The number of pixels by itself doesn’t mean a lot, but rather, when you put it into context with the viewing distance and also how large the screen is. So what matters is pixel density.
KWONG: Pixel density…
CHANG: Yeah.
KWONG: …That’s pixels per square inch. So a 4K TV has 4,000 pixels in a line across the screen. But screens come in different sizes.
CHANG: Yeah.
KWONG: Four thousand pixels could be packed into a 55-inch TV or a 70-inch TV, and that will affect your viewing experience. So, Ailsa, like, say your dad just bought a new 80-inch TV that is 8K – that’s 8,000 pixels across the screen – but he watches it from 10 feet away in a big room.
CHANG: (Laughter).
KWONG: That means he paid too much. He does not need something that powerful.
CHANG: My dad never wants to pay too much for anything, so he would be mad at this.
(LAUGHTER)
CHANG: I wonder if my TV, though, at my house in Los Angeles has too many pixels for me to notice.
BARBER: Yeah, so this is what I was worried about. I just bought a 65-inch TV, and it’s the most I’ve ever spent on a TV. And I was dying to know, did I waste money? I brought it up to Maliha and Rafal Mantiuk, one of the other co-authors. They ran my TV specs through their calculator. I sit about 7 feet away.
RAFAL MANTIUK: I would say that you are exactly where you should be in terms of viewing distance. I think that was, you know, the perfect fit for your, you know, viewing environment.
KWONG: Nice.
BARBER: Validated.
CHANG: (Impersonating French accent) Perfection.
KWONG: Good job, Gina. So lesson here – don’t just buy a super-megapixel TV because it’s the newest model or highest resolution yet. Talk to the people at the store. Tell them the viewing distance in your TV room and buy something that actually fits your needs.
CHANG: Yeah.
BARBER: And, Ailsa, if you’re wondering, like, why computer scientists are so interested in TVs, we should note that this study was funded by Meta because those sorts of insights are also, like, really important for people who make, like, VR goggles, 3D images, this new generation of technology for our eyes.
CHANG: Yeah. OK, well, for our third topic – storytelling and the brain. I feel like NPR would be very interested in this. Gina?
BARBER: Yeah, so there’s a new study out this month in the Journal of Neuroscience that suggests the way a story is told changes how the memory of that story forms in the human brain.
CHANG: OK, so explain this a little bit to me. You’re saying that different versions of the same story might activate my brain in different ways?
KWONG: Yes, exactly. And to figure that out, researchers put participants in MRI machines and told them stories while looking at their brains. So all the participants heard a story about going out to eat with a line that read…
CHARLES FERRIS: Once I was ready to go, I took an Uber to meet my friend at the restaurant.
BARBER: That’s Charles Ferris, a cognitive neuroscientist and one of the study authors. And he says, from there, researchers changed the details. In some cases, they also told the stories with extra sensory details like…
FERRIS: I noticed a scuff mark on my blue shoes as I walked down my staircase towards the front door.
BARBER: Yeah, you can almost picture the story, right?
KWONG: Yeah.
CHANG: Yeah.
BARBER: Like, hearing those details.
KWONG: Right.
BARBER: And with this version of the story, researchers saw more connections between the hippocampus – that’s an area important for memory – and the area of the brain related to sensory integration and language processing.
CHANG: OK, so that was the first version of the story. What was the second version?
KWONG: The second version had more conceptual details instead, so like how the person was thinking or what they felt.
FERRIS: I wanted to take my time getting ready because it was important to me to look nice for my friend.
KWONG: So these details are more related to the emotional context, right? And in this telling of the story, researchers then saw more connections between the hippocampus and areas of the brain related to emotion and conceptual processing.
CHANG: And what does it mean if memories are forming in different areas of the brain?
BARBER: So we asked Charan Ranganath, a neuroscientist at the University of California, Davis. And he didn’t work on this paper, but he does study memory. And he says the study offers two big takeaways – first, how interconnected the human brain actually is.
CHARAN RANGANATH: The standard narrative in neuroscience has always been focused on single brain areas, when something that these authors are showing is that, in fact, memory is this kind of richly orchestrated set of interactions across these brain regions.
KWONG: And secondly, he says this study emphasized that even if the key details of a story are the same, different ways of presenting that information could change the way a person processes it and possibly remembers it.
CHANG: Yeah. OK, note to self, storytellers. That’s Emily Kwong and Regina Barber from NPR’s science podcast Short Wave. Subscribe now for new discoveries, everyday mysteries and the science behind the headlines. Thank you to both of you.
KWONG: Thank you so much, Ailsa.
BARBER: Thank you, Ailsa.
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