Researchers have been studying
the factors that influence us to say yes
to the request of others
for over 60 years.
And there can be no doubt that there's
 a science to how we are persuaded.
And a lot of the science is surprising.
When making a decision
it'd be nice to think that people consider
all the available information
in order to guide their thinking.
But the reality is very often different.
In the increasingly overloaded
lives we lead, more than ever
 we need shortcuts or rules of thumb
to guide our decision-making.
 My own research has identified
just six of these shortcuts.
As universals that guide human behavior,
they are:
Reciprocity,
Scarcity,
Authority,
Consistency,
Liking,
and Consensus.
Understanding these shortcuts and
 employing them in an ethical manner,
can significantly increase the chances that
someone will be persuaded by your request.
Let's take a closer
look at each in turn.
So the first universal principle
 of influence is Reciprocity.
Simply put, people are obliged to give
 back to others the form of behavior,
gift, or service that they
have received first.
If a friend invites you to their party,
there's an obligation for you to invite
them to a future party you are hosting.
If a colleague does you a favor
then you owe that colleague a favor.
 And in the context
of a social obligation
people are more likely to say
yes to those that they owe.
One of the best demonstrations
of the principle of reciprocation
comes from a series of studies
conducted in restaurants.
So the last time you visit a restaurant,
there's a good chance that the waiter
or waitress will have given you a gift.
Probably about the same
time that they bring your bill.
A liqueur perhaps or a fortune
cookie or perhaps a simple mint.
So here's the question.
Does the giving of a mint have any influence
over how much tip you're going to leave them?
Most people will say no.
But that mint can make
a surprising difference.
In the study, giving diners a single
mint at the end of their meal,
typically increased tips by around 3%.
Interestingly if the gift is doubled and two
mints are provided, tips don't double.
They quadruple, a 14% increase in tips.
But perhaps most interestingly of all,
is the fact that if the waiter provides one mint,
starts to walk away from the
table, but pauses, turns back
and says, "For you nice people, here's an extra
mint," tips go through the roof.
A 23% increase influenced not by what
was given, but how it was given.
So the key to using the principle
of reciprocation is to be the first to give
and to ensure that what you give
 is personalized and unexpected.
The second universal principle
of persuasion is Scarcity.
Simply put, people want more
of those things they can have less of.
When British Airways announced in 2003
that they would no longer be operating the twice
daily London-New York Concorde flight
because it had become uneconomical
 to run, sales the very next day took off.
Notice that nothing had changed
about the Concorde itself.
 It certainly didn't fly any faster, the service didn't
suddenly get better, and the airfare didn't drop.
It had simply become a scarce resource.
And as a result, people wanted it more.
So when it comes to effectively persuading others
 using the scarcity principle, the science is clear.
It's not enough simply to tell people
about the benefits they'll gain
if they choose your products and services.
You'll also need to point out what
 is unique about your proposition
and what they stand to lose
if they fail to consider your proposal.
Our third principle of influence
 is the principle of authority.
The idea that people follow the lead
 of credible knowledgeable experts.
 Physiotherapists for example are
able to persuade more of their patients
to comply with recommended
exercise programs
if they display their medical diplomas
on the walls of their consulting rooms.
People are more likely to give change for
a parking meter to a complete stranger
if that requester wears a uniform
 rather than casual clothes.
What the science is telling us is that
 it is important to signal to others
what makes you a credible knowledgeable
authority before you make your influence attempt.
Of course this can present problems.
You can hardly go around telling potential
customers how brilliant you are.
But you can certainly arrange
for someone to do it for you.
And surprisingly the science tells us that it doesn't
seem to matter if the person who introduces you
is not only connected to you but also likely
to prosper from the introduction themselves.
One group of real estate agents were able to increase
both the number of property appraisals
and the number of subsequent
contracts that they wrote
by arranging for reception staff
who answered customer enquiries
to first mention their colleagues'
credentials and expertise.
So, customers interested in letting
a property were told "Lettings?
Let me connect you with Sandra who has over 15
years' experience letting properties in this area."
Customers who wanted more information
 about selling properties were told
"Speak to Peter, our head of sales. He has over
 20 years' experience selling properties.
I'll put you through now."
The impact of this expert introduction led
to a 20% rise in the number of appointments
and a 15% increase in the
number of signed contracts.
Not bad for a small change in
 form from persuasion science
that was both ethical and
costless to implement.
The next principle is Consistency.
People like to be consistent with the
things they have previously said or done.
Consistency is activated by looking for and asking
for small initial commitments that can be made.
In one famous set of studies researchers
 found rather unsurprisingly,
that very few people would be willing
to erect an unsightly wooden board
 on their front lawn to support a Drive
Safely campaign in their neighborhood.
However in a similar
neighborhood close by,
four times as many homeowners indicated that they
 would be willing to erect this unsightly billboard.
Why?
Because ten days previously, they had
agreed to place a small postcard
in the front window of their home that signaled
their support for a Drive Safely campaign.
That small card was the initial commitment
that led to a 400% increase
in a much bigger but still consistent change.
 So when seeking to influence
using the consistency principle,
the detective of influence looks for voluntary,
active and public commitments
and ideally gets those
commitments in writing.
For example, one recent study reduced missed
appointments at health centers by 18%
simply by asking the patients,
rather than the staff
to write down appointment details
 on the future appointment card.
The fifth principle is the principle of Liking.
People prefer to say yes
to those that they like.
But what causes one
person to like another?
Persuasion science tells us that
there are three important factors.
We like people who are similar to us,
we like people who pay us compliments
and we like people who cooperate
with us towards mutual goals.
As more and more of the interactions
that we are having take place online
it might be worth asking whether these
factors can be employed effectively
in let's say online negotiations.
In a series of negotiation studies carried out between
MBA students at two well-known business schools,
some groups were told, "Time is money.
Get straight down to business."
In this group around 55% were
able to come to an agreement.
A second group however, were told,
"Before you begin negotiating, exchange
some personal information with each other.
Identify a similarity
you share in common
then begin negotiating."
In this group 90% of them were able to come
to successful and agreeable outcomes
that were typically worth
18% more to both parties.
So to harness this powerful
principle of liking,
be sure to look for areas of similarity
that you share with others
and genuine compliments you can give
before you get down to business.
The final principle is Consensus.
Especially when they are uncertain,
people will look to the actions and behaviors
of others to determine their own.
You may have noticed that hotels often
place a small card in bathrooms
that attempt to persuade guests
to reuse their towels and linen.
Most do this by drawing
a guest's attention
to the benefits that reuse can
have on environmental protection.
It turns out that this is a pretty effective
strategy leading to around 35% compliance.
But could there be an even
more effective way?
Well it turns out that about 75% of people who
 check into a hotel for four nights or longer
will reuse their towels at some
point during their stay.
So what would happen if we took a lesson
from the principle of consensus
and simply included that
information on the cards
and said that 75% of our guests reuse
their towels at some time during their stay.
So please do so as well.
It turns out that when we do this,
 towel reuse rises by 26%.
Now imagine the next time you stay
in a hotel you saw one of these signs.
You picked it up and you
read the following message:
Seventy-five percent of people
who have stayed in this room
have reused their towel.
What would you think?
Well here's what you might think.
"I hope they're not the same towels."
And like most people
you'd probably think that
this sign will have no influence
 on your behavior whatsoever.
But it turns out that changing
just a few words on a sign
to honestly point out what comparable
 previous guests have done
was the single most effective message
 leading to a 33% increase in reuse.
So the science is telling us that rather than
 relying on our own ability to persuade others
we can point to what many others are already
doing especially many similar others.
So there we have it.
Six scientifically validated principles of persuasion
that provide for small practical,
often costless changes that can lead
to big differences in your ability
to influence and persuade others
in an entirely ethical way.
They are the secrets from
the science of persuasion.
