[ intro music ]
My name is Laurie Santos.
I teach psychology at Yale University,
and today, I want to talk to you about anchoring.
This lecture is part of a series on cognitive biases.
Let’s do a math problem really quickly,
and you’ve gotta do it in your head.
First, multiply the following numbers:
eight times seven times six times five
times four times three times two times one.
OK, that’s it.
What’s your guess?
When the psychologists Danny Kahnemanand Amos Tversky
tried this with human subjects,
subjects on average guessed about two thousand two hundred and fifty.
Seems like an OK guess.
But now, let’s suppose I gave youa different math problem.
What if I gave you this one?
One times two times three times four
times five times six times seven times eight.
What’s your answer?
If you’re like Kahneman and Tversky’s subjects,
your answer might be a bit different here.
For this question, their subjects guessed a lot lower.
On average they said the answer was about five hundred and twelve.
The first amazing thing about these similar mathematical estimates
is that people get the answers really, really wrong.
In fact, the real answer?
Well, for both, its forty thousand three hundred and twenty.
People are off by an order of magnitude.
But the second, even more amazing thing
is that people give different answers to the two problems,
even though they’re just different ways
of asking exactly the same question.
Why do we give completely different answers,
when the same math problem is presented differently?
The answer lies in how we make estimates.
When you have lots of time to do a math problem,
like eight times seven times six times five
times four times three times two times one,
you can multiply all of the numbers together
and get an exact product.
But when you have to do the problem quickly,
you don’t really have time to finish.
So you start with the first numbers.
You multiply eight times seven, and get fifty-six.
And then you’ve gotta multiply that by six, and,
well, you’re guessing the final number’s gotta be pretty big,
bigger than fifty-six, like maybe two thousand or so.
But when you do the second problem,
你从1×2开始计算 呃 才得2
you start with one times two, and, well, that’s only two,
and two times three’s only six.
Your answer’s gonna be pretty small,
maybe only like five hundred or so.
This process of guessing based on the first number you see
is what’s known as “anchoring”.
The first number we think of when we do our estimate is the anchor.
And once we have an anchor in our head,
well, we sort of adjust as needed from there.
The problem is that our minds are biased
not to adjust as much as we need to.
The anchors are cognitively really strong.
In the first problem, you probably started with fifty-six,
and then adjusted to an even bigger number from there.
And in the second problem, you started with six,
and then adjusted from there.
The problem is that starting at different points leads to different final guesses.
Like real anchors,
our estimated anchors kinda get us stuck in one spot.
We often fail to drag the anchor far
enough to get to a correct answer.
Kahneman and Tversky discovered that
this sort of anchoring bias happens all the time,
even for anchors that are totally arbitrary.
For example, they asked people to spin a wheel
with numbers from one to a hundred,
and then asked them to estimate
what percentage of countries in the United Nations are African.
People who spun a ten on the wheel
estimated that the number was about twenty-five percent.
But people who spun a sixty-five
estimated that the number was forty-five percent.
In another experiment, Dan Ariely and his colleagues
had people write down the last two digitsof their social security number.
They were then asked whether they would pay that amount
in dollars for a nice bottle of wine.
Ariely and colleagues found
that people in the highest quintile of social security numbers
would pay three to four times as much for the exact same good.
Just setting up a larger anchor
can make a person who would pay eightdollars for the bottle of wine
be willing to spend twenty-seven dollars instead.
Sadly for us, sales people use anchors against us all the time.
How many times have you noticeda salesperson or an advertisement
anchoring you to a particular price,
or even to how much of a particularproduct you should buy?
Whether it’s buying a car, or a sweater,
or even renting a hotel room,
our intuitions about what prices are reasonable to pay
often come from some arbitrary anchor.
So the next time you’re given an anchor,
take a minute to think.
Remember what happens when you drop your anchor too high,
and then consider thinking of a very different number.
It might affect your final estimate more than you expect.
Subtitles by the Amara.org community