Hey, jerk, don't pee on the floor, please.
I'm Angela Duckworth.
I'm Steven Dubner.
And you're listening to No Stupid Questions.
Today on the show, can posting a sign make people change their behavior?
A sign that says, just think how proud your mother would be to know that you're washing
your hands right now.
Maybe that's the sign we all need.
Steven, we have an email from one Adam Wick of Pittsburgh, Pennsylvania.
City of bridges, city of steelers and pirates and penguins.
And Carnegie Mellon University.
And they also, can we just say apropos of nothing other than the fact that Adam Wick
is from Pittsburgh?
Pittsburgh is a model city in transitioning from what used to be called blue collar work
or heavy industrial to what's sometimes called the knowledge economy.
It's phenomenal.
Yeah.
So anyway, there should be more Pittsburgh's.
It's also just lovely.
So Adam Wick writes, does posting signs cause behavioral change?
And then he elaborates, a colleague approached me at work asking for help in improving the
design of a sign that he was going to post in the men's room.
The sign provided instructions for how to dry your hands with only one paper towel.
Wash your hands, shake them into the sink at least 12 times, grab a paper towel, fold
it in half one time and use it to dry your hands.
Although the method does work well, I'm wondering if even an amazing sign has a chance of creating
behavioral change.
Cheers, Adam Wick, Pittsburgh, Pennsylvania.
I thought this was going to be about how to increase hand hygiene, but it sounds as if
it's more about how to dry your hands with only one paper towel as opposed to more.
It's more about conserving paper towels than about spreading germs.
And there's a whole debate about whether paper towels in a bathroom are better than electric
dryers in terms of energy consumption and so on.
I will say years and years and years ago, I remember writing about how most signs that
encourage people to wash their hands are put in the wrong place, which is over the
sink, which is where the people.
They're already there.
You're preaching to the converted.
Right.
Rule number one of signposting is they need to be in the place where the offenders will
see them as opposed to the cooperators.
But I like Adam's question because I feel like this is at the sweet spot of what you
do and what I do.
He's asking, do signs which are interpreted in our brains and bodies actually change behavior?
If they do work, when do they work and why?
If you think about it, you could imagine a variety of issues with signs.
Maybe people ignore a sign or somehow it just doesn't make an impression.
Maybe it works, but only on a few of the people or maybe it works even for many people, but
then it wears off, the novelty goes away.
And you can even imagine cases in which signs backfire where they perhaps encourage the
behavior you're trying to stop or even decrease the behavior you're trying to encourage.
So I want to talk for a moment about what are called DMS's, dynamic message signs on
highways.
Angela, I'm sure you've been driving or driven around enough to see these increasingly.
Yes.
Yes.
The ones that say your speed is 36 or however fast you're driving.
Yeah.
They can tell you how fast you're going or they can include all different sorts of warning
messages, cautions, things like that.
Like fortune cookie messages, but all about safe driving.
What's your sense, just as an individual human, how that sign might work to change your behavior?
I guess it might work in part because it's new information, so it counters habituation.
And then I guess if you are kind of oblivious to how quickly you're going, which I think
can happen when you are going at a constant velocity, but it's not changing, we don't
have a feeling of going fast.
We can only feel speeding up and slowing down.
So maybe it draws your attention to something you wouldn't otherwise notice.
So all those things even make me feel quite optimistic about the effect of those dynamic
signs.
Well, there is research from the journal Transportation Research Record published in 2021.
The paper is called Does Displaying Safety Messages on Dynamic Message Signs Have Measurable
Impacts on Crash Risk?
They write, safety message data were collected from a total of 202 DMS or dynamic message
signs on freeways across the state of Michigan between 2014 and 2018.
These data were integrated with traffic volume, roadway geometry, meaning you're controlling
for difficult and easy passages of highway, let's say, and crash data for segments that
were located downstream of each DMS.
The results did not show any significant difference with respect to total crashes.
So that's bad news.
Marginal declines in nighttime crashes were observed at locations with more frequent
messages related to impaired driving, like, hey, if you're drunk, get out and walk.
Although drunk walking, we actually argued in supereconomics is more dangerous per mile
than junk driving, but that's a different story.
Maybe for the person who's drunk, but maybe not for other people.
Exactly.
It's hard to kill someone else when you're walking drunk.
But then they write, finally, speeding related crashes were significantly less frequent near
DMS, these signs that showed higher numbers of messages related to speeding or tailgating.
So maybe not hugely positive findings, but that's positive, which might lead one to conclude
that highway signage works, at least to some degree.
Would you accept that as a shorthand?
I will accept that.
I mean, I was at a fundraiser for my husband, Jason, yet another of his philanthropic
slash civic causes.
He's a big advocate of pedestrian safety and cyclist safety.
Anyway, we recently had an event to raise money for this pack aimed at improving the
safety of cyclists and pedestrians in the state of Pennsylvania.
The invited guest was Eric Guerra, who's a professor at my university, University of
Pennsylvania.
And he essentially specializes in the interface of the built environment and transportation,
like highways, crosswalks, signage, and then humans.
So drivers, pedestrians, cyclists.
And I asked him, can you just summarize the literature for me, what works?
One of the things he said is that one of the best ways to do it is not necessarily signs
per se, but actually the roadways themselves.
So you can put up all the signs you want.
But if it's like a huge straight shot, people are going to go really fast.
If you have a really windy, small, narrow road, then people are going to go slower.
So I think a lot of the innovation here is not signs per se, but the structure of where
we're driving itself.
But that said, if you're working with a built environment that's already built,
which of course many safety experts are, you think, what can I add?
And if you add signs, this paper from Transportation Research Records seems to show there's some
gain to that.
But you knew there was a butt coming, did you not?
There's always a butt.
There's an even more recent paper published in Science by Jonathan Hall and Joshua Madsen.
Jonathan Hall is an economist at the University of Toronto.
The other Madsen is a professor of accounting, University of Minnesota.
And they write the following.
Although behavioral interventions are designed to seize attention,
little consideration has been given to the costs of doing so.
In other words, that sign up there, we want it to produce a benefit.
Might it cost something too?
They write, we estimated these costs in the context of a safety campaign
that to encourage safe driving displays traffic fatality counts
on highway dynamic message signs for one week each month.
That was such antiseptic language.
Fatality counts, like the number of people who have died.
Yeah, like eight people died on this highway in the last month, let's say.
And again, there seems to be an experimental instrument here,
which is the signs are only going up for one week each month,
which means that you can measure the week they're up and when they're down.
Very clever.
Ah, you know, that is possibly going to have the effect of distracting me
just because it's so kind of like, oh my God.
And by the way, since it didn't tell me how fast I was going,
it distracts me and doesn't necessarily get me to slow down either.
Right. It doesn't put you in with the group of speeders or not speeders.
It puts you in with the group of alive versus dead.
And all of a sudden you just saw the number of dead.
I'm going to predict that it is either neutral because the costs equal the benefits
or I don't know, possibly bad. I'm not sure.
I'll read on here from the paper by Hall and Madsen.
We found that crashes increase statewide during campaign weeks.
That means the weeks when the signs are running,
which is inconsistent with any benefits contrary to policymakers expectations.
They write.
We found that displaying fatality messages increases the number of traffic crashes.
So they conclude back of the envelope.
Calculations suggest that this campaign again,
a campaign that's designed to save lives causes an additional
twenty six hundred crashes and sixteen fatalities per year in Texas alone
with a social cost of three hundred and seventy seven million dollars each year.
How nuts is that? Or maybe if you're Angela Duckworth and you know the way
the human mind works, maybe it's not so nuts.
Well, look, I'm not going to pretend that I could have guessed that right off the bat.
I could see it going either way, but I'm curious whether these
scientists had any explanation for why it is.
They propose a number of hypotheses and the one that they land on one proposed
explanation they write for the surprising finding is that these quote in your face
or quote sobering negatively framed messages sees too much attention.
That is, they are too salient, interfering with drivers ability
to respond to changes in traffic conditions.
So, Angela, I am really glad that this question about
how to fold a paper towel to dry your hands has brought us to this question,
which I consider a little bit higher stakes because it's not just with traffic safety.
It's with a lot of things.
I keep coming across this word salience in psychology, but also in econ papers, too,
which is this argument that once you become aware of something,
when something becomes fully or largely salient,
it really affects our behaviors in ways that you might not anticipate.
Can you just talk about salience from your perspective for a minute?
There's an aperture, if you will, that can be fully dilated and you're completely aware of
something or completely closed where it's happening, but you just didn't notice.
Say there's a sign by the side of the highway that you didn't look at.
For you, it didn't exist.
So salience is the extent to which something enters your field of view, your awareness,
and it can be anywhere from zero to 100 percent.
When we're in the flow state and we're completely engaged in activity,
all of our attention is going to what we're doing.
And the opposite of that would be like complete neglect.
But in a more complicated interaction, let's say you're driving down the highway,
you see the sign.
What these scholars are arguing is that salience increases essentially
bad outcomes of traffic crashes.
How can that be?
Because attention is going to the sign.
So I look up and I'm probably not only looking away from what's in front of me,
perhaps for that moment, and this is complete speculation, the emotion of that.
Like, you know, two people died on this highway in the last year.
I maybe have memories or thoughts triggered of people I know who died.
I mean, who knows what's going on?
But basically, I want to make the point that when we talk about attention,
it's not only attention to this object versus that object,
the sign versus the odometer or the steering wheel versus the person next to me.
But there's also a kind of internal spotlight.
Is my attention going to one thought or the other thought?
When someone's driving, you really want their attention externally to be
on the cars around them and then internally to be on driving.
I guess that's not the scenario I was.
I was picturing a scenario whereby it's not that I'm distracted in the moment by the sign
and get in a crash within the next half mile.
It's that I read that and I think about, oh, my goodness, this thing I'm doing is dangerous.
Theoretically, it could make me more careful, but theoretically, it could make me tense up.
We know that most of us don't respond well to pressure.
If you look at test taking and sports and things like that,
it takes a lot of practice and experience to deal well with pressure.
That was the mechanism that I was imagining was the response to salience.
But I don't know. We're both speculating here.
I don't think this study, just from what they did, would be able to say that one
account is more right than the other. By the way, they're both possible,
but they both do start with attention going to that sign.
It does remind me of another story.
I bet you know this story because this is a famous story and it was popularized by
someone that you are a great admirer of. Do you know the story of the Petrified National Forest
in Arizona and what happened there?
I do know the story. This is Bob Cialdini, yeah?
This is Bob Cialdini. This was some time ago and I don't know the story that well,
but from what I recall, it goes something like this.
There's the Petrified Forest National Park in Arizona where Cialdini lives.
The problem is that people would go in and steal pieces of petrified wood and crystals
from the forest floor. That's plainly not good for the integrity of the forest.
They would just put it in their pocket to take home and put on a shelf.
I think all of us can imagine that sentiment. It's just like, oh my gosh, it's so cute.
It's one little thing.
And there's so much of it.
It's a whole forest. And so as he described it, there's a sign, as you come in the park,
that says because so many people are stealing wood at the rate of nearly a ton a month,
this is undermining the integrity of the forest.
So Cialdini had a graduate student working with him.
The student and his fiance went to the forest and saw the sign.
And the student said that before he even finished reading the sign,
he heard his fiance say to him, oh, we better get ours now before it all disappears.
So he was wondering, like, what on earth could possibly produce that sort of result?
Cialdini, being a scientist, turned this into an experiment.
And they ended up putting up a sign or a number of signs in front of different pathways running
through the forest. And they actually, as he put it, salted those pathways with pieces of petrified
wood. And then they looked to measure the effect of the sign on stealing the wood.
In other words, if we have a sign that says, please don't steal the wood, too many people
stealing wood, da, da, da, what happens?
Compared to no sign, right?
Compared to no sign and having the sign tripled the rate of theft. Is that salience? Is that what
that is?
It's salience, but signs always convey something in addition to that, which is some kind of message.
And in the case of the petrified forest, it is signaling to you, everybody steals wood
from the petrified forest. What's wrong with you? Why haven't you stolen your piece yet?
It's conveying a social norm in the terminology that Cialdini might use.
I think you also want to think about what that sign is doing then in this bathroom that Adam
talks about. The sign provides instructions for how to dry your hands with only one paper towel,
et cetera. I think in some ways what this sign might be doing is that if it just says, like,
don't forget to wash your hands, it's communicating to you. You probably would have forgotten. We have
to scold people. We have to put up a sign in the bathroom because nobody's washing their hands.
It's not communicating that. It's communicating with this kind of pro tip,
this hack so that you can only use one paper towel. That to me is really important because
as a practical matter, you want signs that are not only going to bring things to the top of mind to
make things salient, but also carry some information that makes people more inclined
as opposed to less inclined to do the wanted behavior.
So, Angie, I do think it'd be really interesting to hear from listeners about signs that have
worked or failed to work on them maybe. What do you think?
I think that would be fantastic. I want to hear sign stories.
Send us your sign stories. Make a voice memo. Just make a recording with your phone. Do it
nice and clearly. Include your name. And email it to us at NSQ at Freakonomics.com. Maybe we can
share it in a future episode. Still to come on No Stupid Questions, what happens when even the
most intelligent, informed people refuse to follow the signs? They were going to jump out from their
hiding spot, scowl at them, and then take their name and publicly post it to shame them.
Now, back to Stephen and Angela's conversation about how signage affects human behavior.
When we see a sign, I think one thing we don't necessarily think hard about, but we feel,
is who's the author of that sign? Who is the authority figure who's posting it or asking
that it be posted? And who is the intended beneficiary of the behavior? It could be you.
It could be other people. And also, is the message of the sign kind of dictatorial or is it more
collaborative? Is it complementary? Is it insulting? One of the most famous examples
from the book Nudge by Thaler and Sunstein was about putting an image of a fly, a housefly,
on a urinal in the airport. I think it was the airport in Amsterdam. Thaler and Sunstein didn't
come up with this. They just thought it was a great example of nudge framework, which is,
if you're a guy standing there ready to pee, rather than peeing on the wall or on the floor,
which men sometimes do, if there's a fly, oh, it's a game. I have a target. I'm going to pee
on the fly. And so that's a sign, but it does a couple other things too. It does gamify it.
It makes it fun. And it makes you a participant in the behavior as opposed to a sign that says,
hey, jerk, don't pee on the floor, please. You know, I read that little anecdote and I
not an expert on men's urinals. Not having a penis, I just missed it as a useless anecdote.
Has it kind of taken off? Are there little cute targets in men's urinals all over the world
because of this trick? A lot of people read that book Nudge. I've definitely seen flies or bull's
in more urinals than there used to be, but I would not say it's universal.
I think there should be more of that. And I do think that is not only a reminder,
but it's communicating something which is certainly not insulting or dictatorial.
I mean, I have a memory of this speed sign in a part of a suburb of Philadelphia where I used to
live called Narberth. And there was this long cul-de-sac, a street called Narbrook Park.
And in the park, there was a speed limit sign that said seven and a half miles.
