
Agatha Christie's clever detective novels may reveal more about the inner workings of the human mind than she intended. In this podcast, a look at what scientists uncover when they treat words like data.
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Jad Abumrad
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Sergei Pakhomov
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Jad Abumrad
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Sergei Pakhomov
Okay.
Jad Abumrad
All right.
David Snowden
Okay.
Jad Abumrad
All right. Listening to Radio Lab. Radio Lab short from wny, see and npr. Hey, I'm Jad Abumrad.
Robert Krulwich
And I'm Robert Kilwich.
Jad Abumrad
Yep. This is Radiolab. And today, just to start things off for this podcast. All right, let's just say that you love an author, but somehow the text isn't enough.
David Snowden
Okay?
Jad Abumrad
It doesn't get you close enough to the author. So what do you do?
Robert Krulwich
You know, what you do? But take off your shoes, you take off your stocks, and you stand on the book. You stand on the book and your whole body says, let me in.
David Snowden
Let me in.
Jad Abumrad
Yeah, let me give you a different flavor of that. Hello. How about you take the text, give it to this guy, he puts it into a computer and you turn it into data.
Robert Krulwich
What do you mean? Who is that?
Jad Abumrad
This is.
Ian Lancashire
My name is Ian Lancashire. I'm a professor of English at the University of Toronto.
Jad Abumrad
Now, Ian, as he said, is an English professor, but he's also a computer guy, right?
Ian Lancashire
Founded a computing center of IBM Canada.
Jad Abumrad
And the reason he combines those two is because he's interested in the secrets behind the author's words that desire, he says, to take a text, spin it into data as a way to get into that author's head. Well, that goes back a long way.
Ian Lancashire
Goes back to the fathers of the Christian church, to the Bible in the early Middle Ages.
Jad Abumrad
So monks decided that to make what's called a concordance of the Bible. And what that means is that we're going to take every single word in the Bible. And there are 960,243 of them, at least in the King James Version. And they were going to list them all alphabetically, notate each time, every single word was used. And the context.
Ian Lancashire
Yes. Imagine it. You begin with the first verse. In the beginning, you create a heading for the first word in. And then for the second word, the. And then for the third beginning. Every time you come across those words, you have to write a context.
Jad Abumrad
In Genesis 1, verse 1, occurrence 1, in the beginning. Genesis 1, verse 6, occurrence 2. And God said, let there be firmament in the midst.
Ian Lancashire
It's all handwritten. And at the end, you end. Well, you end up with a lot of pieces of paper.
Jad Abumrad
So many that it took those first monks who decided to do this an entire lifetime to complete it. Nowadays, you know, with computers, you can be done in.
Ian Lancashire
In under 15 seconds.
David Snowden
Bam.
Jad Abumrad
So that all just basically sets the stage for the story that I'm about to tell you. It's the 1980s. Ian is an English professor at Toronto. He's got a lab full of computers, and he's using them to analyze his favorite authors.
Ian Lancashire
Samuel Taylor, Coleridge, T.S. eliot, James Joyce, Cadman, Chaucer, Shakespeare.
Jad Abumrad
And he's turning up some interesting stuff.
Ian Lancashire
Sort of, for example, in his poetry, Milton didn't use the word because who knows why?
Jad Abumrad
Yeah. But at a certain point, Ian decided to look at more modern authors.
Ian Lancashire
And so I turned to Agatha Christie.
Jad Abumrad
At the time, he was doing this. We're now in the 90s. Agatha Christie happened to be the most published author ever.
Ian Lancashire
She sold a billion books.
Jad Abumrad
A billion? Like B billion.
Ian Lancashire
She was number one behind God after. After the Bible, I think. So what I did is I collected two of her earliest novels written in the early twenties.
Jad Abumrad
You fed those two into the computer.
Ian Lancashire
Then I did the third.
Jad Abumrad
Eventually, you would add in 14 additional books that cover 50 years of Agatha Christie's writing. What is the computer doing exactly?
Ian Lancashire
Measuring the individual concordance, word frequency, vocabulary of the works.
Jad Abumrad
And all the while, it's spitting out these reports.
Ian Lancashire
And I saw the totals at the bottom.
Jad Abumrad
Now, first of all, the woman wrote 80 detective novels, which is just amazing in and of itself. The computer found that her use of language was relatively consistent and normal for the first 72 of those books. But something happened on book number 73, something drastic.
Robert Krulwich
What?
Jad Abumrad
Suddenly, her use of words like words.
Ian Lancashire
Like thing, anything, something, nothing.
Jad Abumrad
What Ian calls indefinite words.
Ian Lancashire
These. These words increased six times.
Jad Abumrad
But also when the computer added up the vocabulary size of that book, that.
Ian Lancashire
Is, how many different words are there in the first 50,000 words of a text?
Jad Abumrad
It found in this book? There were 20% fewer different words.
Ian Lancashire
That is astounding. That's 1/5 of her vocabulary lost.
Jad Abumrad
It gradually dawned on him that what he might be seeing was the very beginning stages of an author losing herself.
Ian Lancashire
She had developed Alzheimer's. I delayed publishing my results for two years. I had to have the results analyzed by computational linguist and a statistician.
Jad Abumrad
And in her lifetime, was she ever actually diagnosed?
Ian Lancashire
Absolutely not. There was no diagnosis.
Jad Abumrad
He said that some of her biographers suspected that something was up in her later years.
Ian Lancashire
At one point, apparently she cut off all her hair. She was not doing very well in.
Jad Abumrad
Interviews, but as far as we know, she was never taken to a doctor, never got diagnosed.
Ian Lancashire
I think her family closed around her and protected her. I realized that I was seeing something about the human mind. I was seeing the author in the text in a way that people hadn't seen the author in the text before.
Jad Abumrad
Which raised a question for me, and I think this can apply to anyone. We all write a bazillion emails a day. I've got a decade's worth on my computer. Does that stuff hold clues about what we'll be like, early warning signs?
Ian Lancashire
I think it's possible it does, yes. And it's well worth doing research about how a loss of vocabulary can be determined, let's say in one's email over five or six years.
Jad Abumrad
Indications are, he says, that those clues are there. Not only that, they may actually be there practically from the beginning. Oh, yep.
Ian Lancashire
A very famous example is the so called nun study.
Sister Alberta Sheridan
Okay.
David Snowden
The nun study actually began in 1990.
Jad Abumrad
This is Dr. Kelvin Lim. He works at the University of Minnesota and is the current director of the so called NUN study. And this study, more than any other that we know, really makes the point about the predictive power of the words we choose. The study began with a guy named David Snowden who wanted to look at aging over time. So he chose nuns because he wanted a group that was healthy.
David Snowden
For example, they don't smoke, they don't.
Jad Abumrad
Drink, they all have similar lifestyles.
David Snowden
Obviously haven't had children.
Jad Abumrad
So he approached this one particular order.
David Snowden
In Connecticut called the School Sisters of.
Jad Abumrad
Notre Dame, and he signed up just short of 700 nuns. And the only stipulation being you had.
David Snowden
To be at least 75 years of age. And so we're now 20 years in the study. So that means the youngest of the sisters is about 95.
Sister Alberta Sheridan
Yeah, I think I am. I am the youngest.
Jad Abumrad
And you are 94 years old.
Sister Alberta Sheridan
Yes, sir.
Jad Abumrad
Not 95?
Sister Alberta Sheridan
Not 95.
Jad Abumrad
This is Sister Alberta Sheridan.
Sister Alberta Sheridan
I like the way you said that.
Jad Abumrad
Do you happen to know who the oldest remaining sister in the study is?
Sister Alberta Sheridan
Wait a minute. No. The one who was buried today, Jane, was 101. I think she was the oldest one in the study in our province. Yes.
Jad Abumrad
The study began innocently enough. She says researchers would show up to the convent every year, give the nuns.
Sister Alberta Sheridan
A bunch of tests, like, mostly from memory, just questioning back and forth.
Jad Abumrad
And then over the years, as the nuns passed away, which many of them.
Sister Alberta Sheridan
Have at this point, they've all gone.
Jad Abumrad
Jed. Of the original 678 sisters, at this.
David Snowden
Point we have approximately 40 sisters still alive and participating in the study.
Sister Alberta Sheridan
And I'm the only one left here in the Wilton province.
Jad Abumrad
And as the nuns would pass away, the researchers had arranged it so that they would get a small piece of their brains.
Sister Alberta Sheridan
Yes.
Jad Abumrad
Which they could examine for plaques and tangles.
Sister Alberta Sheridan
Now, this morning we buried a sister here. I told you. But the funeral was delayed a bit because she had to be taken to the hospital to have a portion of her brain removed to further the study.
Jad Abumrad
Okay, so here's why I bring this study up. Because of an accident that happened pretty early on that changed everything in the study. David Snowden, the main dude, was in the convent archives and he was talking to the archivist. The archivist says to him, hey, you know all these nuns that you're studying who right now are over the age of 75. I actually have the essays that they wrote right when they got here.
David Snowden
And they did this roughly at about.
Jad Abumrad
Age 18, like 60 years before.
Sister Alberta Sheridan
Oh, yes.
Robert Krulwich
Oh, yeah, right.
Sister Alberta Sheridan
I have a copy of his at home.
Jad Abumrad
Oh, that's great.
Sister Alberta Sheridan
Come on in, Naomi.
Ian Lancashire
Thank you so much.
Jad Abumrad
We actually asked a reporter, Naomi Stereben, to visit Sister Alberta at her home in Connecticut and have her read her essay that is now 76 years old.
Sister Alberta Sheridan
Yeah, go ahead. Two days after the birth of the Christ Child, I was brought as a belated Christmas gift to a Mr. And Mrs. Albert Joseph Sheridan of Providence, Rhode Island. A week later, the sparkling Waters of baptism were poured over me. I'm not going to read all this silly stuff when I first entered.
Ian Lancashire
Why not?
Sister Alberta Sheridan
It sounds kind of saccharine. I was only a teenager when I wrote.
Jad Abumrad
But here's the thing. When the researchers found the essays like the one you just heard, it was a gold mine.
David Snowden
It was a major, major find.
Jad Abumrad
So they analyzed the essays, looking primarily.
Sergei Pakhomov
At two specific features of the language that was contained in these narratives.
Jad Abumrad
That's Sergei Pahoma. He does the analysis for the current nun study.
Sergei Pakhomov
Particularly, they looked at the notion of grammatical complexity and idea density.
Jad Abumrad
What is idea density? What does that mean?
Sergei Pakhomov
Idea density is a measure that looks at how many basic units of meaning are contained in any given utterance, divided by the total number of words in that utterance.
Sister Alberta Sheridan
In other words, the date of my birth is December 27th.
Jad Abumrad
Like if you were to listen to Sister Alberta's autobiography.
Sister Alberta Sheridan
When I was 11 years of age, my dear mother was called to God.
Jad Abumrad
It's the number of little discrete ideas she's able to cram into one sentence.
Sister Alberta Sheridan
This was to be a turning point in my life, as I had always had the ardent desire to become a sister.
Jad Abumrad
Here's a classic example of the difference between low and high idea density.
Sergei Pakhomov
Here's low from Sister Helen. I was born in Eau Claire, Wisconsin on May 24, 1913, and was baptized in St. James Church.
Jad Abumrad
Okay, that's low.
Sergei Pakhomov
Now here's high from Sister Emma. It was about a half hour before midnight between February 28th and 29th of the leap year 1912, when I began to live and to die as the third child of my mother, whose maiden name is Hilda Hoffman and my father, Otto Schmidt.
Jad Abumrad
I gotta say I'm liking the first one, Jed.
David Snowden
Probably you as a journalist seen the first one as straight to the point.
Jad Abumrad
Yeah, it's good writing.
David Snowden
And the second one seems kind of embellished a little bit.
Jad Abumrad
Yeah, but here's the punchline of all this. Turns out that the people who when they were 18, wrote in that journalistically very precise, low idea density sort of way, those people 60 years later were vastly, vastly more likely to develop dementia. In fact, based on those essays alone, the researchers could Predict with about 85% accuracy what the nuns brains would look like when they died and were able to look at the brains. Would the brains have plaques and tangles that you associate with Alzheimer's or would they not? What?
Robert Krulwich
I mean, that's just crazy.
Jad Abumrad
Wait, why?
Robert Krulwich
It's backwards reasoning. But we'll see, we'll see. I'm Just suddenly I'm suspicious. Here's a man who, from what you just said, has found the ones who got sick and working backwards, found certain incidences of this, that or the other, and says, ah, this is a cause that produces this effect.
Jad Abumrad
No, no, no, no. There's no cause and effect here.
David Snowden
These studies are demonstrating associations, right? They're not demonstrating causality. It's a very important distinction.
Jad Abumrad
This is just a correlation.
Robert Krulwich
Okay, but, you know, that may be one of 190 correlations that produce people who get Alzheimer's in the end.
Jad Abumrad
Yeah, I mean, yeah, I mean. But let me argue your case actually from a different angle. Like, would this kind of linguistic analysis actually be relevant in the age of Twitter, where everything is short and click short.
Robert Krulwich
But people who Twitter don't only Twitter. They might also write small, short, dense essays for their.
Jad Abumrad
Yeah, but, well, you know, I guess you're. All right. It's like it's mostly about the thoughts in your head, not so much what you write.
Robert Krulwich
Well, so what about Agatha Christie? Was there a conclusion about Agatha.
Ian Lancashire
Yeah, there was Agatha Christie writing Elephants Can Remember.
Jad Abumrad
This brings us back to Ian Lancaster and that 73rd book of Agatha Christie's that he analyzed, found that her vocabulary dipped well. Before he did the analysis. He picked up that book and gave it a read. And like most people who read it, didn't like it.
Ian Lancashire
Initially I thought it was very poorly written, badly plotted, full of errors of time of dating, terrible read. Then I realized when I looked at the title, Elephants Can Remember, he realized.
Jad Abumrad
That maybe Agatha Christie sensed what was happening to her.
Ian Lancashire
She was responding to that truism that elephants never forget. The chief character is an aging female novelist named Ariadne, who is a foil for Agatha herself. And she, Ariadne, is suffering from memory loss.
Jad Abumrad
In the story, she tries to help a detective solve this crime, but she has trouble because she keeps forgetting.
Ian Lancashire
And the last sentence in that novel, in fact, is Agatha saying, well, maybe it's okay not to remember.
Jad Abumrad
Wow.
Ian Lancashire
She was trying to defend herself, defend her sense that she was forgetting. She was losing her vocabulary, she was losing her language. I began to see that Christy was heroic, still writing despite this handicap and her willingness to do that at an age of 81, 82, struck me as heroic in a way.
Robert Krulwich
I understand that the muse wouldn't quit, but the. The tools all left the room.
Jad Abumrad
Yeah, I think we should leave the room.
Robert Krulwich
Okay.
Sister Alberta Sheridan
Message eight from phone number seven.
Jad Abumrad
Hello, this message is for Radiolab.
Sister Alberta Sheridan
My name is Paulina, I come from Chile. I'm a big fan of Radiolab and this is your credits. The Radiolab podcast is funded in Power by the National Science foundation and the SLO Foundation. Take care. Bye. End of message.
David Snowden
Rideiolab is supported by the National Forest Foundation, a nonprofit transforming America's love of nature into action for our forests. Did you know that national forests provide clean drinking water to 1 in 3Americans? And when forests struggle, so do we. The National Forest foundation creates lasting impact by restoring forests and watersheds, strengthening wildfire resilience, and expanding recreation access for all. Last year, they planted 5.3 million trees and led over 300 projects to protect nature and communities nationwide. Learn more at nationalforests.org Radiolab.
Sergei Pakhomov
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Jad Abumrad
Yeah, crushed it.
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Original Air Date: May 5, 2010
Hosts: Jad Abumrad and Robert Krulwich
“Vanishing Words” explores the hidden, often startling information encoded in the words we use—how the way we write and speak can reveal critical information about our minds, even predicting onset of conditions like Alzheimer’s decades before symptoms appear. Hosts Jad Abumrad and Robert Krulwich talk to researchers and analyze two intriguing stories: the shifting language of Agatha Christie late in her prolific career, and a groundbreaking study involving nuns whose youthful writing foretold mental decline many years later.
“That is astounding. That’s 1/5 of her vocabulary lost.”
— Ian Lancashire [06:03]
“She was losing her vocabulary, she was losing her language. I began to see that Christie was heroic, still writing despite this handicap…”
— Ian Lancashire [15:52]
“Nuns [writing in] that journalistically very precise, low idea density sort of way... 60 years later were vastly more likely to develop dementia.”
— Jad Abumrad [12:59]
“These studies are demonstrating associations, right? They’re not demonstrating causality.”
— David Snowden [13:56]
“I understand that the muse wouldn’t quit, but the … tools all left the room.”
— Robert Krulwich [16:26]
The episode weaves curiosity, empathy, and wonder—hallmarks of Radiolab’s storytelling. There’s gentle humor in self-examination and interviews. Strikingly, it ends not in morbid fascination with decline, but with admiration for human creativity and resilience, even as words begin to vanish.
For anyone who hasn’t heard “Vanishing Words,” this episode offers a breathtaking look at how the most ordinary acts of writing reveal the hidden currents of our minds, the inevitability of decline, and the dignity with which we might face it.