Hank Green: Are you eating a credit card's worth of plastic every week? 

Uh, probably not. 

But if you saw headlines like this, you might worry that you are.

These days, trying to piece together what to believe can feel impossible, but we can still find reliable, trustworthy answers as long as we know how to look for them.

Hi, I'm Hank Green, and welcome to Crash Course Scientific Thinking. 

[Theme music] 

You probably already know that you shouldn't believe everything you read, watch, or hear.

On an internet where everyone is competing both for attention and to control narratives, it's no surprise that there are plenty of distortions, exaggerations, baseless claims, propaganda, and whatever this is [a labubu].

But it's also home to lots of good scientific information, too. So, when it comes to something as important as science, how do we figure out what's reliable?

Well, it helps to understand how a science story like like this becomes news in the first place. 

See, that CNN article isn't the whole story. It's just the part we see as consumers of science. 

[Bites into potsto electricity science experiment] That science news tastes bad.

Think of it like he tip of the iceberg. There's a lot more going on below the surface. 

CNN got the details from this report by the WWF. No, not the wrestling group from the 90s, the World Wildlife Fund for Nature.

And they got it from the study they commissioned from researchers at Australia's University of Newcastle, which reported a range of possible amounts of plastic that people might consume in a week from a high on 5 g, all the way down to 0.1 g.

But the WWF only reported the high end of the range, saying an average person could be ingesting approximately 5 g of plastic per week, about the size of a credit card. 

And that technically could be true. It could be that much. There's a lot of things that could be true. 

It's like when an insurance company says, "I could save you up to 15% or more on your car insurance." Up to 15% or more, that's all the percents. So why would they do that? 

Well, different kinds of publications have different kinds of goals. And as a savvy consumer of science media, it's helpful for you to consider what those goals might be. 

Like the WWF is a non-profit advocacy group whose goal is to preserve nature through lobbying and research. 

So, they might really want to sound the alarm about microplastics in order to bring people into their broader mission. 

Considering an outlet's goals gives us as consumers more information to consider. It gives us a broader context than just the story would alone. 

And while I would agree that microplastics are a big deal, only reporting on the upper range to make the situation feel more urgent and headline-worthy can make a situation seem a lot more dire than it actually is, and intentionally or not, be misleading. 

News organisations, by the way, also have goals that we should take into consideration. Like the goal to get a lot of people to click on an article. 

And a headline that says, "You might eat between a tenth of a gram and 5 g of microplastics every week" is not going to get the clicks.

What gets reported in the news is sometimes different from the information in the primary source, the firsthand account from a scientific study. 

The primary source is the most accurate representation of what the scientists who conducted the research actually found. 

In this particular instance, the primary source was the study from the researchers at Newcastle who reported a range of possible amounts of plastic ingestion. 

So what happened between the primary source and CNN?

Well, the Newcastle team got their results and shared them with the WWF. It was then written into a report by consultants who had not conducted the research directly in what we would call a secondary source. And this secondary source only listed the upper range of plastic we could be eating. 

Those are the numbers that got picked up by CNN.

In science, news articles are often tertiary sources. They summarise the information of primary and secondary sources and are usually not written usually not written by scientists.

Sometimes when science gets reported, it can also gets distorted. Sometimes it's an honest mistake. Someone somewhere along the way got their facts mixed up. 

We call that misinformation, information that is wrong or misleading. 

But because, as the kids say, we live in a society, we also have to worry about disinformation, information that is intentionally misleading or false. 

But here's the thing, none of this means that we have to stop trusting reputable news organisations or even advocacy organisations like the WWF wholesale. It just means we need to be more diligent when we are consuming news. 

And good science journalists have learned to navigate the scientific community. They often have experts they can reach out to for second opinions, and they present useful context behind a story to help them reader understand how the news fits into larger conversations in science. 

So, what does this mean for us? How can we, non-scientists and non-journalists, dig down and figure out when a story is reliable and when it isn't?

I think it's time for some sage advice. 

[Sage advice title card]

Sage: That's key, Hank. You don't dig, you sift. 

It's a way of evaluating sources developed by digital literacy expert, Mike Caulfield from the University of Washington. 

The S stands for stop. When you see something that triggers a strong emotional response, you should stop and really think about what you're reading. 

Hank: So don't immediately text everyone I know and tell them that they could book a flight with all of the microplastics inside of them. Got it. What's next?

Sage: I, investigate the place that published the information. Who's putting it out there and why? 

In this case, we're looking at CNN. How do we find out if CNN is a reputable source? Well, we know they've been around for over 40 years, but let's investigate a bit further. 

So, let's open a new tab and get the scoop on CNN.

It looks like they're in the green zone on this media bias chart from Harvard Library's research guides. 

We call this strategy lateral reading, checking other websites, newspapers, and media guides, like this one, to make sure that the source you're getting the original information from is on the up and up. 

Hank: So, if the original source is trustworthy, then we're good? 

Sage: Uh, not yet.

Up next is F, find better coverage. Using those same lateral reading skills, we need to check if other sources are reporting the same thing. What are other outlets reporting?

In this case, we can find some other sources citing the credit card stat, but we can also find reputable sources saying that it's misleading.

If other reputable sources are disagreeing, it's a sign to take the source you found with a grain of salt.

If other sources are agreeing, then it's a good sign you can dig deeper into what you read. 

Hank: So, you've got to read not just beyond the headline, but beyond the first source, especially before you share it. 

Sage: Then you won't be surprised to hear... the T.

T is for trace claims to their original context. 

This is a big one. Often, when we see quotes or images online, they're being taken out of context. 

So, tracing them back to their origin can help us figure out if we're seeing the whole story. 

In this case, the CNN article tells us that the credit card claim comes from the WWF article, which CNN links to.

There, we can see that they got the claim from this original study. 

And here, we can see the information in its original context, which stated, "Humans may ingest 0.1 to 5 g of microplastics weekly." Not "You're eating a credit card!" Much more nuanced.

So, the high end of this range, which was in the original report, is actually 50 times greater than the low end of the range. That's a lot!

And this has been your sage advice. 

[Title card]

Hank: Thanks, Sage. 

Okay, so SIFT is awesome, and in an age where we're getting so much of our news from social media, it's more important than ever for us to be discerning about the information that we are absorbing and sharing. 

Like, you will almost never see a primary source in a TikTok video. That should raise immediate red flags and encourage you to start sifting. 

Also, ChatGPT and other generative AI tools do not pass the SIFT test. They are not trustworthy as primary sources. 

And I get it. Fact-checking can feel like a lot of work.

For me, the SIFT method is a great tool, but there are other fact-checking methods out there, and the one you use and how you use it is a personal choice.

But, reliability isn't. Some sources are just more reliable and more trustworthy than others and our personal biases don't  change that. 

Like, the WWF might be an organisation that does a lot of of good, but they're still an advocacy group, which is going to advocate for a certain cause and that might mean occasionally misrepresent scientific information. 

The point is, anytime we're looking at any source of science information, we have to remember that reputation and motive are among the most important things we should be looking for when it comes to sources. 

There might be conflict of interest like with the WWF or even an obvious lack of reliability or trustworthiness when we start sifting through our sources.

Thinking critically about the sources we're getting our news from is one of the best ways to make sure we aren't consuming a credit card's worth of bad information every week. 

But, it's not foolproof. Even the SIFT method will let us down sometimes. 

Like we learned back in episode 1, none of us are immune to bad information, but tools like lateral reading are some of the best shields we have against the tide of mistruths. And I think you'll find that as you start to sift through the sources, the trustworthy ones will rise to the surface more often than not. 

In our final episode, we're going to explore the crossroads of science and public perception. I'll see you then. 

This episode of Crash Course: Scientific Thinking was produced in partnership with HHMI BioInteractive, bringing science stories to thousands of high school and undergrad life science classrooms. If you're a teacher, visit their website for resources that explore the topics we discussed in this video today.