Short Wave - Why Big Numbers Break Our Brains

Episode Date: January 3, 2024

In celebration of our 1000th episode, we're wrapping our heads around big numbers. Educational neuroscientist Elizabeth Toomarian talks about why humans' evolutionarily-old brains are so bad at comprehending large quantities–like the national debt and the size of the universe–and how to better equip ourselves to understand important issues like our finances and the impacts of climate change.Interested in other ways our brains make sense of the world? Email us at [e-mail]. See pcm.adswizz.com for information about our collection and use of personal data for sponsorship and to manage your podcast sponsorship preferences.NPR Privacy Policy

You're listening to Shortwave from NPR. Hey, short wavers. Today's episode is a special one for us because it's in celebration of our 1,000th episode, which, wow, I think we look great for 1,000. But how do you even process a thousand of something? This milestone got us thinking about big numbers and how it's hard to wrap your brain around them sometimes. So we called an educational neuroscientist. My name is Elizabeth Tumarian. From Stanford, University.

University. One of the things she studies is how the brain processes numbers or doesn't. Our human brains are pretty bad at comprehending large numbers. And the same is true, actually, for really small numbers, too. And needing to think about a nanosecond or a billion of something is a pretty new thing for humans. Our brains are evolutionarily very old, and we are pushing them to do things that we've only just recently conceptualized. Things like the size of our universe, or or the National Dead, or understanding how many seconds are in a year. For example, think about a piece of ticker tape representing the amount of time between us and when the Big Bang happened about 13.7 billion years ago.

Where would you place the existence of the dinosaurs on that tape? Our intuitive sense would be like, oh, we think about dinosaurs as being a really long time away, and so we might put that really close to the Big Bang. Or maybe somewhere near the middle of the tape. when in reality, that's not right at all. Like dinosaurs are really close to us in like, I think it's like in the last, you know, couple inches of a multi-yard thing of ticker tape. Today on the show, navigating the modern world with an ancient brain,

we ponder the struggle that is processing big numbers and then figure out how to get better at it. I'm Regina Barber. You're listening to Shortwave, the science podcast from NPR. Okay, Elizabeth, let's dig into how our brains process numbers in general. Okay, I understand that there's a couple of different systems at play when we think about numbers. How do our brains process single-digit numbers? Okay. So I think one thing that is helpful to start to think about is that our brains are really processing how much of something or how many of something there are in our environment. And then as humans, we have created these sort of cultural inventions to help us have a shorthand for how much or how many there are. And that's our number system. So when we have something like,

you know, the number one, the digit Arabic numeral one or two or three or four, young kids have to be taught to tie their understanding of what's in the world to this arbitrary symbol that we're telling them means a certain amount. And so we have to be taught. And so we have to have a couple of different theories for how this works. And we think that humans and kids really process one, two, three, even four, and five in a certain way. And once we get above that, we're really processing it in a totally different way. We're actually might even be using a different brain system altogether to estimate how much of something there is in our environment. Okay, so let's talk about like real big numbers now. So like now we're beyond five and six,

beyond like 100. And to do that, can you describe the mental number line? So the mental number line is what scientists think we do to make sense of the numbers around us. And so for the majority of people, we tend to think about numbers in the same way that our writing systems and number systems are culturally devised. So for those of us who primarily, for example, speak English or any kind of language that goes from left to right, right, we write on a page from left to right, that tends to be how our mental number line is also organized. So you can think of that as small numbers on the left, large numbers on the right. Think of it as being like a ruler in space in front of you. And we know that from when you're much younger, that your mental number line is pretty compressed.

So a kid who's five, six, seven years old probably doesn't have a lot of experience with numbers that are much greater. than 10, 50, 100. And so once you get beyond that, sort of everything is just sort of really big. On the right side. And as you get older, this number line that was sort of compressed at the end becomes a bit more linear. You're sort of pushing the boundary of the numbers that you can comprehend and make sense of. So when you ask people to place a million on a number line between zero and a billion, they're much more likely to put it sort of right in the middle. And we know that a million should be much closer to zero than it is to a billion. Right.

And so people tend to be really bad at judging the difference between number words that we use quite often and actually really understanding what do they represent in terms of how much they are. Even the idea of the difference between a millionaire and a billionaire, like, that's huge. Right. But they tend to get kind of lumped together in that way. Okay. So why do you think our brains are so bad at comprehending these people? big numbers. So our brains are bad at comprehending big numbers because they're not actually intended to

be doing these sorts of things. Our brains are evolutionarily very old, and we are pushing them to do things that we've only just recently conceptualized. And so our brains are designed really to help us understand generally how much of something is in our environment or how many of something, but it's not really built for doing these really precise exact calculations. We certainly can use our brains in that way, but we're recycling these sort of evolutionarily old brain architectures to do something really new. So it's not our fault, but it's helpful to understand why this is really a challenge, and then what can we do to help people?

I like how you say it's not our fault because in a 22 article you wrote for the publication and the conversation, you say that our brains are really built more to compare than to count. Right. Like what does that mean or what does it look like? Yeah. So our brains are really meant to help us with things on a day-to-day basis, like what is closer to me, that tree or that tree? Or, you know, in modern life example, at the grocery store, which line is going to be shorter? Which one am I going to get through checkout faster? And so we have an entire brain system that is really helping us make those estimations that are based on generally how much of something is in our environment. But we're having to sort of use those structures along with other brain

networks to do something like, how much money do I need to save for retirement, or, you know, how much data do I have on my phone, or whatever other kinds of day-to-day things we're encountering now. Numbers are part of our everyday lives, and we're having to use these same kinds of brain systems to help us make sense of those kinds of numbers as well. Yeah. So what are some of the consequences of not comprehending big numbers? So to me, I think that some of the really important consequences tend to come down to things like financial decision making, whether it's on a day-to-day basis or a long-term basis. I think it's really hard to estimate, like how long is 30 years of my life or 50 years of my life? What does that mean in terms of what I have to save every day? And

you know, a million dollars sounds like a lot of money, but then you really, there's, there's interesting calculations there to try to understand, you know, is that actually meaningful? I mean, it also makes me think of science literacy, right? And like numbers and climate change and all these like percentages that are like going around in the news and voting. Yeah. You know, numbers are part of our everyday lives. They are important in political ways in terms of policy. So, you know, whether it's understanding the enormity of certain challenges that we face, you know, as a group in terms of climate change, understanding time scales and how close or far we are from certain kinds of outcomes. That's really important.

Yeah, I mean, I think that even understanding the impact of different policy decisions on things like, you know, the budget and deficits and taxes and really understanding the ramifications of those and what that money is going towards and, you know, that involves ratios, percentages, is estimation, really big numbers and smaller numbers. And so I think that's another day-to-day kind of example where really understanding what our biases are and what kind of strategies we can use to help ourselves make sense of big numbers is really important. So if we're so bad at understanding these big numbers, how can we get better at understanding these big issues? So a couple of strategies that we leverage to really make more sense of these big numbers are

things like using metaphors and analogies, bringing them down to human scale. So making sure that there's a tie to something that we do have a good understanding of. Also, visualization is a really powerful tool. So whether we're talking about public health or public policy or climate change or even just understanding, I don't know, how many cockroaches there are on Earth, You know, how many plastic water bottles could go around the circumference of the earth. Or, you know, if you really want to have people understand, like, a consumer decision, nine out of ten dentists recommend XYZ toothpaste. Like, that is something that people can really wrap their minds around.

They can picture 10 people. They could picture nine out of those 10 people. But if you say something like 92% of dentists, it sort of does something a little bit different. Like, it is really helpful to bring it down to scale. and tying it to something that's relevant in day-to-day life and tying it to something maybe that has emotional value is another strategy. And so unless we're using things like metaphors, making things really personal to us, being able to use visualizations. That's why data visualization is so important. Unless we use the tools that are available to help ground those numbers in something

that is meaningful, it's very easy to be dismissive. Thank you so much, Elizabeth, for breaking this down for us, for helping me understand why I don't understand big numbers. Thanks for having me. And thank you short waivers, whether you've been here since the beginning or just listening for the first time to this episode. We love learning and exploring the universe with you. Speaking of learning, we're going to link the article we mentioned earlier that Elizabeth co-wrote with Lindsay Hasek. It's called Brains Are Bad at Big Numbers. making it impossible to grasp what a million COVID-19 deaths really means.

It inspired this episode. This episode was produced by Brilly McCoy, edited by a showrunner Rebecca Ramirez and fact-checked by Susie Cummings. Maggie Luthor was the audio engineer. I'm Regina Barber. Thank you for listening to Shortwave from NPR.