Hi, my name is David Pizzaro, I'm a psychologist at Cornell University and I
study emotions, especially emotions and how they influence judgement.
Today I want to talk to you about one of those emotions, the emotion of disgust
and how it might influence your thinking in surprising ways.
For a long time psychologists have pointed to the power of emotions.
In fact emotions are those things that motivate us toward action.
Many times these emotions are things that motivate us toward actions that would
keep us alive. For instance our strongest emotions,
emotions like fear are ones that keep us from getting close to natural predators.
There's a reason why we're afraid naturally of things like lions and snakes
and spiders. But emotions don't only motivate us to
behave in certain ways like avoiding predators.
They also seem to change the way we think about the world.
That is when your'e fearful, not only do you want to run from the lion, but you're
more likely to think that there are lions everywhere.
And this influence on judgement has some interesting effects.
What I want to talk to you about today is the power that the emotion of disgust
might have on the way we make our judgments.
And how a very natural emotion that keeps us away from things that might
contaminate us or give us diseases also changes the way we think about our
social, moral, political, and even our consumer decisions.
Now, the insight that emotions could even be studied systematically probably first
came from Charles Darwin. Who wrote a book in the late 1800s
systematically documenting the universal nature of many human emotions.
Psychologists in the 60s picked up this original project of Darwin's and
documented that across the world there appeared to be a set of universal basic
emotions and these as I said, are the kinds of emotions that were, are around
and universal because they help us adapt to our natural environment.
So for instance, we have fear, surprise, disgust, anger.
All of these are there in the human system, in the human mind, in the human
body because they give us a certain kind of survival advantage.
Disgust is one of these basic universal emotions.
That is no matter where you look, no matter what culture you look to,
somebody, people seem to have this natural adversive response to things that
are gross. Things that might contaminate us or give
us diseases. This is a good emotion.
It keeps our bodies clean, right, disease is something that we've had to deal with
throughout most of human history. So avoiding disease with this natural
program of disease avoidance, that we might call disgust, is a very good thing.
You can see the origins of this even early in infancy.
if you take a bitter liquid or sour liquid and you put it into the mouth of
an infant, a newborn, what you'll see is something very much like the full blown
adult disgust face. They'll wrinkle up their nose.
They'll even protrude their tongue trying to get that thing out of their mouth.
In fact when we make a disgust response, even though we can't see that we're
sticking out our tongue, we're often actually moving our tongue in that same
way. So, one of the things that's very
interesting about disgust and actually one of the reasons I started studying it
was because it's very, very easy to make people disgusted.
Some of the other emotions are hard to influence in the laboratory.
That is we can bring people in the lab and we can try to make them angry.
We can try to make them afraid with various methods.
But disgust we don't have to try very hard.
I'm just going to give you one example of a disgusting image I'll just prepare you
in advance that I'm about to show you something disgusting.
Some of you might actually show that same emotion face that I just showed you where
you wrinkle up your nose. Right.
This is something that we might see in any day in, in, in our lives but it's
something that probably has a profound ability to make you feel disgust.
Some of you might feel it more than others.
And in fact when we look at the sorts of things that make us feel disgusted across
cultures we see a very common pattern. As I said, these are things that tend to
make us sick if we touch them or come into contact with them.
So things like feces, urine, blood, vomit, rotten flesh, pus, all of those
things are universal triggers of disgust. That is to say although we can override
them sometimes. No matter where you look people seem to
respond with the same reaction. And the, it makes sense.
These things are also things that might actually make us sick.
They're signs of disease. Now, when Darwin was investigating the
emotions, he wrote something that I think was very insightful.
he says here in Tierra del Fuego, a native touched with his finger some cold
preserved meat while I was eating and plainly showed disgust at it's softness.
While I felt utter disgust at my food being touched by a a naked savage, though
his hands did not appear dirty. So one of the things that Darwin is
pointing out early on is that the same disgust reaction that he has, he saw in
the savage. This was an early documentation of the
universe, universal nature of disgust but Darwin also points to something
interesting, that is, that we not only feel disgust for things that might
contaminate us by putting it in our, putting it in our mouth, or maybe by
touching it, but we also feel disgust very easily at people, other people,
people that might be foreign from us. And he also points to the fact that
disgust, one of the real important features of disgust Is that it works
through contagion. To give you an example, if you stand next
to a lion I might be afraid of the lion but I'm not now afraid of you.
Disgust doesn't work that way. If you touch something disgusting, now
that thing has the property of disgust. That is, through this association with
the bad thing. That has now been contaminated and I
don't want to touch it. And if you think about it, this is a very
good thing if what we're trying to avoid is disease.
So before we had an explicit theory of how germs spread and cause disease, the
emotion of disgust was tracking contagion.
The power of contagion is at work a lot in, in the emotion of disgust.
Especially as we navigate our daily social moral political lives.
but also when we make our consumer decisions.
Let me give you an example from one study.
researchers gave individuals a mug and asked them, how much do you think this
mug is worth? This was compared to a group who were
just asked, how much do you think this mug is worth.
but we're not given the mug, and it turns out in general people think that their
own, their own things are worth more. So if you say how much would you sell
this mug for, how much is worth? If I've just given it to you, you'd
actually think that it's worth more. But if I showed you disgusting images
like the one I just showed you before, that effect goes away.
One of the most robust effects, that we like things and we value things that are
our own more than those things that belong to others, can be completely wiped
out if we are now feeling disgust when evaluating the value of our own product.
In another set of studies If products that are disgusting touched products that
were not disgusting so in this case a product that has to come into close
contact with the body. They used tampons.
If tampons touched a bag of cookies, mind you both of them were closed and they
were clean tampons. There was no chance of any contamination
going on. Just the fact that people were disgusted
slightly by the tampons made them value the cookies less.
Now this property of contagion that we can see in consumer decisions extends to
what might be considered a very a much more important domain.
That is we can make you feel disgusted not at cookies or a mug, we can make you
feel disgusted about a person or an entire social group.
This has been used quite effectively and quite tragically in many cases.
One of the best cases comes from World War 2 propaganda, where the Germans were
trying to convince people that the, that the Jews were filthy, disgusting
individuals in, in part to make it easier to kill them.
So, this comes, this quote comes from a Nazi children's book published in 1938.
Trying to point the children to the disgusting, the disgusting features of
Jewish people. It says just look at these guys!
The louse-infested beards! The filthy, protruding ears, those
stained fatty clothes. Jews often have an unpleasant sweetish
odor. If you have a good nose you can smell the
Jews. More recently this very same tactic has
been used by people who want to convince us that homosexuality is bad or immoral.
So this is taken from an anti-gay website, gays are worthy of death for
their vile sex practices, they're like dogs eating their own vomit and sows
wallowing in their own feces. Again, these very low level discussed
properties, pointing to human bodily products for instance or, or specific
descriptions of sexual acts get the disgust reaction going, and through the
process of contagion, we tag an individual or an entire social group, and
it gives us a very, very strong avoidance and negative response to that group.
Now, one of the questions that my colleagues and I wanted to answer was are
some people just more prone, more susceptible, to being convinced by this
process of contagion. And so, one of the things that we wanted
to look at was, well, maybe some people who are more easy to disgust than others
would be more likely to have some kind of negative attitudes toward certain social
groups. And we were able to do that by looking
across the population at, simply put, the levels of squeamishness that individuals
have. Just as with many other basic universal
notions, while we all have them, some of them have them much stronger than others.
So in this class, there are many of you who when I showed that image had a very,
very strong response, some of you weren't even bothered at all and wondered why I
bothered to put the picture up. We can actually measure this level of
squeamishness using a scale called the disgust sensitivity scale and plot people
along the line of how easily disgusted they are in everyday life and how hard to
disgust they are. we do this by asking a series of
questions. Let me give you a couple of examples.
Imagine that you were asked this. Even if I were hungry I would not drink a
bowl of my favorite soup if it had been stirred by a used but thoroughly washed
fly swatter. How much do you agree or disagree with
that statement? Or, while you're walking through a tunnel
under a railroad track, you smell urine. Would you be very disgusted or not at all
disgusted at? It turns out that I'm actually very very
disgusted so it's hard for me to do this research.
But we can plot a score given enough of these questions that gives you an overall
score on how discussed sensitive you are, how squeamish you are.
One of the things that this can do is predict your actual behavior.
So the researchers that came up with the scale brought people into the laboratory
and asked them to do a variety of tasks that were disgusting.
For instance, eat perfectly healthy, in fact very nutritious, meal worms but that
nobody eats worms really in the United States so they were very disgusting.
or something milder like eat a piece of chocolate that's been baked to look like
a, to look like dog poop. it turns out people find, people who are
very easily disgusted are much less likely to do that than people who are not
easily disgusted. So your score on this scale actually
predicts your actual disgust response and your behavior.
One of the first things we found was that disgust sensitivity, that is level of
squeamishness, seems to predict of all things, political orientation.
As people who are more likely to be politically conservative were also more
likely to say they were easily disgusted. Another way of saying this though, is
that people who report being more liberal are less easy to disgust.
You might imagine why one way or the other might make more sense.
But this is the general relationship. And we found this over three, four, five
different data collections looking at different populations.
Until we finally came to a very very big data set at least when speaking about
psychology, we were able to look at nearly 30,000 respondents in the United
States, what you see on this graph is that people who are very conservative
there on the right, are much more likely to report that they are easily disgusted.
That's higher numbers there indicate their more squeamish.
And on the other hand, people were very liberal or actually less likely to be
easily disgusted.. We found this even though we were able to
statically control for a variety of factors that we know are related both to
disgust sensitivity and to political orientation like socioeconomic status,
income, education levels, religiosity even some of the biggest personality
traits that we know are associated with both.
No matter what we still found a general relationship between disgust sensitivity
how easily disgusted you are and your political beliefs.
And this actually predicted not just how you respond on a one to seven scale of
how politically conservative you are or liberal, but it also seemed to predict
actually voting behavior. That is when we look at state by state
voting results in the 2008 US presidential election, what we found was
that levels of disgust sensitivity in a state predicted the margin of victory of
Obama over McCain. That is, states that had, in general,
higher levels of discussed sensitivity. Where, states where McCain actually got
more votes compared to Obama. Now, we were wondering whether this was
maybe just a feature of American politics.
So, we looked across the world. Across 121 different countries.
Here, you see collapsed into a number of geographical regions.
We ask the same kinds of political questions and discuss sensitivity
questions. And what we were able to see was these
numbers indicate the strength of the relationship the correlation between
discuss sensitivity and political orientation.
What you see is no matter where you look across the world the samae result
emerges. That is by enlarged the more likely you
are to be easily disgusted the more likely you are to be politically
conservative. Or again you are liberal if you are not
usually discussed it. Now this is a fairly small effect this
accounts for a small part of why we might have political beliefs.
But nonetheless it's interesting because most people might not think that how
easily disgusted they are by things like on flush toilets or speak to strangers
soda. Might actually predict who they vote for
in a presidential election. One of the questions that we had was
whether we could actually shift people's attitudes towards social groups and moral
and political attitudes in particular by making them disgusted.
So what we did at Cornell in our lab was bring participants into the lab.
And asked them to fill out a series of questionnaires.
In this particular study we asked them to evaluate certain social groups.
We knew that there was a strong link between homosexuality and disgust.
Because of the way that many people who are anti homosexual talk about the sex
act and use disgust in order to convince people.
So we wanted to see if if making people disgusted in a completely unrelated way.
That is we weren't making them disgusted about sex or anything like that.
We were making them disgusted with a fould odor.
Essentially we sprayed with a really nasty odor on every other day, and we
brought participants into the lab, and asked them what they thought about
certain social groups. African-Americans, the elderly,
immigrants, gay men, and lesbian women. And what we found was, that the foul odor
had a particularly strong effect In fact, the only effect we found, was that it
made people negatively evaluate gay men more.
So that is, on the days when people had to evaluate gay men, where there was a
foul smell in the room, they were more likely to find, to report greater
negative attitudes. Here, this is plotting on a feeling
thermometer. That is, from zero to 100, how warmly, or
coldly, do you feel toward gay men. Other labs have also looked at these
differences using physiological measures, you might wonder self report, that is if
you ask, if I ask you how easily disgusted you are, maybe you're not so
accurate. But if I hook you up to physiological
measures, measures of heart beat, and skin conductance that we know are rough
measures of arrousal, and show you disgusting images We find the same
general effect. People who report being greater
conservatives, more likely to be politically conservative, are more
physiologically aroused when presented with disgusting images.
Liberals are less physically aroused. In particular, attitudes towards
homosexuality and abortion were the ones that predicted more, most, whether or not
people would be aroused by disgusting images that had nothing to do with those
issues such as dog feces. Well, there's another way to kick in this
feeling that there might be contamination in the environment.
So discussed is a particularly powerful way to do this, but discussed again, is
in the service of keeping us from getting sick.
You can show similar effects by just reminding people that there is disease
prevelant in the environment. And a number of researchers have used
this disease avoidance As a manipulation. We thought, well, perhaps just reminding
people that there's contamination in the environment might get them to change
their political and moral attitudes. So, we conducted a study where all we did
was remind people that the swine flu was, was prevalent in Cornell and that they
should sanitize their hands. In one case we explicitly told them that
they should sanitize their hands. And asked them a number of, of questions
about their moral beliefs and their political beliefs.
In another case we actually just asked them to fill out a questionnaire, either
next to a hand sanitizing station or not. And what we found is, was that a simple
reminder to wash your hands actually had a pretty strong effect on your moral
beliefs. In this case beliefs about sexually weird
but harmless practices. Let me give you an example.
so we asked people, imagine that Joe is house sitting for his grandmother and Joe
invites his girlfriend over and they have sex on his grandmother's bed.
Now, if I'd just reminded you that you should wash your hands because of the
swine flu, you're more likely to find that to be morally wrong that if I had to
be. When we asked people to report their
political orientation in their same set of studies we also found general effect
that simply reminding people to wash their hands had a change in how
conservative there reported being politically conservative.
So a simple reminder of of disgust or of contamination can change our consumer
decisions. It can change our political decisions, it
can change our moral decisions. This is a case in which disgust is not
simply preventing us from eating things that might make us sick but it's having a
fairly profound influence on our social, political, moral judgements.
The question that I want to leave you with is now that we know this, we can
finally get to the point where we can ask when should emotions influence our
thinking? Science isn't particularly well-suited to
answer this question. All we can do is point out how emotions
work. How emotions can influence the way we
make decisions and judgements. But we have to now ask the additional
question, now that we know that, should disgust shape the way, for instance, you
will. Who you vote for in the political, in the
political elections, what you vote for about gay rights, or what you buy at the
grocery store. Thank you very much.