Translator: Ruth Milligan
Reviewer: Rhonda Jacobs Hello. It's a great honor
to give this talk today. How many of you
would like to be successful in life? Raise your hand. Alright? Well actually, the two most important
keys to success in life are: intelligence, and self control. Guess which one you can do the most about. (Laughter) Self control, right? There are pills to cure
just about everything, but unfortunately, there are no pills
to cure low levels of intelligence. (Laughter) My talk is going to focus on self-control. In the 1960s and 70s,
a Stanford psychologist developed an ingenious way
to measure self-control in children. He put a marshmallow
in front of them, and told the kids, "You can eat it now if you want, but if you wait until I come back,
you can have two marshmallows." He tested hundreds of kids, and then did follow-up tests
on them decades later. And what he found is that kids
who waited for two marshmallows, were much more successful in life. They had higher standardized test scores, they were more likely
to graduate from college, they had happier marriages, lower divorce rates, lower obesity rates. The kids who ate one marshmallow
immediately, they all went to jail. (Laughter) Just kidding, just kidding. They didn't go to jail. But in one of these studies, the researchers found that the kids
who waited for two marshmallows, had more activity
in the pre-frontal cortex. That's the part of your brain in charge of, thinking, reasoning,
and emotional control. Psychologists call these
'executive functions.' So poor self-control is actually
responsible for many problems in life, and many of these are preventable, such as health problems, eating unhealthy food,
not wanting to exercise, addictions to the internet or alcohol,
tobacco, just to name a few. [off the mark.com TODAY'S SPECIAL
IS THE "RESOLUTION BUSTER"... A FATTY STEAK SMOTHERED IN FRENCH FRIES,
MARINATED IN HARD LIQUOR, STUFFED WITH CHOCOLATE CAKE
AND TOPPED WITH A CIGARETTE...] (Laughter) People also have trouble
controlling their finances. Some people spend
more money than they make. Sometimes governments do this too. (Laughter) Some people have trouble
controlling their sexual desires, including some politicians. (Laughter) And this can lead
to very difficult consequences. And people also have trouble
controlling their anger. Indeed, anger is the emotion people
have the most difficulty controlling. (Laughter) And sometimes anger
can even lead to criminal behavior. For example, by far the greatest
cause of murder is anger. (Laughter) Really! (Laughter) No other cause even comes close,
like drugs, nothing even comes close. Anger is the leading cause of murder. So speaking of criminal behavior, two criminologists wrote
a very influential book called A General Theory of Crime. What a brazen title! What general factor could cause all crime? Is it bad parenting? Bad genes? Substance abuse? Poverty? Frustration? No, actually, the best predictor
of criminal behavior, especially violent criminal behavior, is poor self-control. So, for over 25 years, I've spent
my career studying human aggression. And aggression often starts
when self-control stops. What I'd like to do today is tell you about a few studies
that we've conducted on the link between
low self-control and aggression, but before I do, I want to tell you
a little bit more about the brain, because, the brain plays
such a critical role in self-control. The human brain's
about the size of a grapefruit. And although it's only about
two percent of our body weight, it uses 20-30 percent
of the calories we consume. The brain is a very demanding organ. Calories provide fuel for the brain
that it uses for many functions, including those executive functions
I talked about earlier: thinking, reasoning,
and emotional control. Also recall, that the emotion people have the most
difficulty controlling is anger. Now food... gives us calories. I don't know if you've
noticed this or not, but sometimes when people
don't get enough food to eat, they have trouble controlling their anger. Hungry people tend to be cranky,
irritable, angry. How many of you know
what I'm talking about? (Laughter) I thought so. There's actually a term
to describe this; it's called 'hangry.' (Laughter) Hungry plus angry. Hangry. Now we actually did
the first experimental study to test whether hangry is a real thing. I'd like to point out,
it's really important that we use science to test what ideas
are true and which ones are false, rather than relying on hunches,
intuitions, gut feelings, common sense, instincts, because those can differ dramatically,
for different people, and they can often lead us astray. So I'd like to tell you about
our experimental study on hangry. Participants were college students. They fasted for food and water for three hours
before they came into our lab. That's a very long time
for college students. (Laughter) First, they participated in what
they thought was a taste test study, and we randomly assigned them
to drink lemonade that was either sweetened with sugar, which has calories
and therefore provides fuel for the brain, or the lemonade was sweetened
with Splenda, a sugar substitute, with no calories,
and hence, no fuel for the brain. In a blind test task,
people can't tell the difference between the lemonade
sweetened with sugar, and the lemonade
sweetened with Splenda. Then we had to measure aggression. Well, this is kind of tricky, right? Because researchers can't just
give participants guns and knifes and see what they do with them. (Laughter) So researchers have to come up
with safer ways to measure aggression. Now, aggression is any behavior
intended to harm another person who wants to avoid that harm. And in this study,
and in the studies I'll tell you after, we used a noise blast procedure, that I developed
for my doctoral dissertation. So let me tell you about
this noise blast procedure. In this procedure, participants compete
with an ostensible opponent, to see who can press
a mouse button faster, when a target square turns red. The winner gets to blast the loser
with loud noise through headphones. (Laughter) The noise levels range
from level 0 to level 10. We included 0 because we didn't want
to force people to behave aggressively. If they don't want to behave aggressively,
they don't have to, they can just choose 0. Level 1 is 60 decibels,
2 is 65, 3 is 70, 4 is 75, all the way up to level 10,
which is 105 decibels. That's about the same volume
as a fire alarm going off directly into your ears
through headphones. (Laughter) The winner also gets to control
how long the loser suffers (Laughter) by setting the noise duration,
from 0 seconds to 5 seconds. Now, the noise is a combination
of noises that many people really hate, like fingernails scratching
on chalkboards, dentist drills, blow horns, sirens. And they do this task 25 times, so we can get a more reliable
measure of aggression. So I know you're dying to hear this noise, so actually, I have a sound level meter, so I can tell you
how many decibels this is. Okay, so here you go. (Screeching noise) (Noise ends) Do you want to hear it again? (Audience) No! 93 decibels. 93! It goes up to 105. So, we told participants that the study was about the effects of different kind
of foods on a reaction time, but it was not. The study was about the effects
of glucose on aggression. And we explained this to participants
after the study was over. So here are the results for participants who drank the lemonade
sweetened with sugar, and those who drank the lemonade
sweetened with Splenda. Those who drank the lemonade with Splenda were significantly
more hangry and aggressive. Why? Because the Splenda
has no calories for the brain. Well, we wanted to replicate
this study; scientists like to do that. We also wanted to see
if the effects generalize, because after all,
this was a laboratory experiment. It was conducted in an artificial
setting - psychological laboratory. Study lasted less than an hour. And the participants were college students
who aggressed against a complete stranger. So, we conducted a field experiment
as a follow up study. In this field experiment, participants
conducted the study in their own home, a natural setting. Study lasted 23 days,
rather than less than an hour. And the participants were actually
married couples, (Laughter) who aggressed against their spouse. (Laughter) So, we had 107 married couples. They'd been married
about an average of 12 years, and on Day 1,
we brought them in our lab, we gave them a standardized measure
of marital satisfaction. We wanted to control for this, because couples who were satisfied
with their marriage, may be less angry and aggressive
with their spouses than those who are not. We also gave them a blood glucose
meter; we showed them how to use it. We sent them home with it,
and for the next 21 days they measured their blood glucose levels
every morning before they ate breakfast, and every evening,
before they went to bed. We also gave each person, (Laughter) a Voodoo doll, along with 51 pins. We told them that this doll
represented their spouse. (Laughter) Every night before they went to bed, they stabbed between 0-51 pins
into the doll, (Laughter) depending on how angry they were
with their spouse that day. They did this alone
with their spouse not being present. (Laughter) And we actually developed this
Voodoo doll task, and we validated it in several studies
involving couples. We like it a lot because
it's an objective measure, you can count the number of pins
between 0 and 51. It doesn't use self-reports. And it also takes some effort
to put the pins in the doll. One participant stabbed all 51 pins
in the doll on one of the days. Actually, on two of the days. (Laughter) Man, I'm glad I'm not
married to that person. (Laughter) So, I bought 250 of these dolls;
they're $20 each. One day I got a call
from my credit card company. (Laughter) They said, "Did you really spend
$5,000 on Voodoo dolls?" (Laughter) I said, "Yeah, I did; I'm a scientist, and I'm doing a study
that involves over 200 participants, and each of them gets a Voodoo doll. And they said, "Really?" (Laughter) I said, "Yeah, really!" They said, "Okay. It seemed like
a suspicious charge to us. (Laughter) We never saw anybody spend
$5,000 on Voodoo dolls before." So on Day 23,
we brought them back in the lab, and they did the noise blast task
that I described earlier. Did you want to hear that noise again? (Audience) No. Okay, I didn't think so. But this time, their partner
was their spouse rather than a stranger. And here are the results. First, the number of pins
stabbed in the Voodoo dolls. Participants with high levels of glucose,
a standard deviation above the mean, and those with low levels of glucose. (Laughter) One standard deviation below the mean. Those with low levels of glucose
were much more hangry at their spouse, and they stabbed almost three times
more pins in the Voodoo doll than those with high levels of glucose. Next, the noise blast. Participants were nicer to their spouse
than college students were to strangers. Those with high levels of glucose, and those with low levels of glucose. But those with low levels of glucose, were once again more hangry
and aggressive with their spouse, than those with high levels of glucose, because they had less energy
for their brain to exercise control over angry feelings
and aggressive impulses. Also we found the number of pins
participants stabbed in the doll was directly correlated
with the intensity and duration of noise blast they gave their partner, which adds some validity
to our Voodoo dolls measure. So, the take home message from this study is don't talk about anything important
with your spouse on an empty stomach! Don't do it! Right? Instead, you should talk
about it over dinner, or better yet, after dinner, after your glucose levels
have had a chance to increase. So we've shown that hangry people are more aggressive
against complete strangers, in our laboratory experiment
involving college students, and hangry people are also
more aggressive against loved ones using our field experiment
involving married couples. So it's really important
that we feed our brain, our brain needs fuel
to engage these executive functions, including controlling angry feelings
and aggressive impulses. Now I am not advocating
that we feed our brain with junk food. Right? Although sugary foods
cause a quick spike in glucose, you get a decrease just as quickly, right? And also we know
that sugary foods lead to diabetes. And we've done other research showing
that people with diabetic symptoms tend to be more aggressive
than those without. So I'm not advocating this. Rather, I'm advocating
that we feed our brain with healthy foods, such as fruits, veggies, and whole grains, that will keep our glucose levels higher
for a longer period of time and at a more stable level. In my office, I have a drawer
full of protein bars so I don't get hangry
with my colleagues and students. So everybody knows that muscles
can be strengthened with exercise. But what many people do not know
is that self-control can also be strengthened
with exercise, just like a muscle. So here's some self-control exercises.
You can try these at home! Work on your posture. Use your non-dominant hand
for mundane tasks like stirring soups, or opening doorknobs,
or brushing your teeth, or drinking beverages. Speak in complete sentences. (Laughter) It's a tough one, huh? (Laughter) Keep track of what you eat. My colleagues actually
did a really cool study in which they randomly assigned
participants, college students, to do these self-control exercises,
for just two weeks, every morning between 8 am - 6 pm. Participants in the control group
did not do the exercises. Then they gave them a standardized
measure of aggressiveness. It has items like: "Once in a while I can't control my urge
to strike another person." (Laughter) "If I have to resort to violence
to protect my rights, I will." Then after two weeks, they came in the lab and they did the noise blast task
that I described earlier. Don't worry, I won't give you
those noise blasts. And here are the results. As you can see, those in the control group,
the more aggressive they were, the louder and longer noise blast
they gave their partner. But check this out, after just two weeks,
those in the self-control exercise group were significantly less aggressive
than those in the control group. So in conclusion, control your anger
and you will live long and prosper. Like I said at the beginning,
the two keys to success in life are intelligence, and self-control. And although it's difficult
to raise your intelligence, you can increase your self-control
by engaging in the exercises I described, and by not being hangry. Thank you. (Applause)
