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Mariano Sigman and Dan Ariely: How can groups make good decisions?

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We all know that when we make decisions in groups, they don't always go right -- and sometimes they go very wrong. How can groups make good decisions? With his colleague Dan Ariely, neuroscientist Mariano Sigman has been inquiring into how we interact to reach decisions by performing experiments with live crowds around the world. In this fun, fact-filled explainer, he shares some intriguing results -- as well as some implications for how it might impact our political system. In a time when people seem to be more polarized than ever, Sigman says, better understanding how groups interact and reach conclusions might spark interesting new ways to construct a healthier democracy.

- Neuroscientist
Mariano Sigman combines neuroscience, mathematics and social sciences to illuminate the hidden information flowing through our brains. Full bio

- Behavioral economist
The dismal science of economics is not as firmly grounded in actual behavior as was once supposed. In "Predictably Irrational," Dan Ariely told us why. Full bio

As societies, we have to make
collective decisions
00:12
that will shape our future.
00:15
And we all know that when
we make decisions in groups,
00:17
they don't always go right.
00:19
And sometimes they go very wrong.
00:21
So how do groups make good decisions?
00:24
Research has shown that crowds are wise
when there's independent thinking.
00:27
This why the wisdom of the crowds
can be destroyed by peer pressure,
00:31
publicity, social media,
00:34
or sometimes even simple conversations
that influence how people think.
00:36
On the other hand, by talking,
a group could exchange knowledge,
00:41
correct and revise each other
00:45
and even come up with new ideas.
00:46
And this is all good.
00:48
So does talking to each other
help or hinder collective decision-making?
00:50
With my colleague, Dan Ariely,
00:55
we recently began inquiring into this
by performing experiments
00:57
in many places around the world
01:01
to figure out how groups can interact
to reach better decisions.
01:02
We thought crowds would be wiser
if they debated in small groups
01:07
that foster a more thoughtful
and reasonable exchange of information.
01:10
To test this idea,
01:15
we recently performed an experiment
in Buenos Aires, Argentina,
01:16
with more than 10,000
participants in a TEDx event.
01:19
We asked them questions like,
01:23
"What is the height of the Eiffel Tower?"
01:24
and "How many times
does the word 'Yesterday' appear
01:26
in the Beatles song 'Yesterday'?"
01:29
Each person wrote down their own estimate.
01:32
Then we divided the crowd
into groups of five,
01:34
and invited them
to come up with a group answer.
01:37
We discovered that averaging
the answers of the groups
01:40
after they reached consensus
01:43
was much more accurate than averaging
all the individual opinions
01:45
before debate.
01:49
In other words, based on this experiment,
01:50
it seems that after talking
with others in small groups,
01:53
crowds collectively
come up with better judgments.
01:56
So that's a potentially helpful method
for getting crowds to solve problems
01:59
that have simple right-or-wrong answers.
02:02
But can this procedure of aggregating
the results of debates in small groups
02:05
also help us decide
on social and political issues
02:09
that are critical for our future?
02:12
We put this to test this time
at the TED conference
02:14
in Vancouver, Canada,
02:17
and here's how it went.
02:19
(Mariano Sigman) We're going to present
to you two moral dilemmas
02:20
of the future you;
02:23
things we may have to decide
in a very near future.
02:24
And we're going to give you 20 seconds
for each of these dilemmas
02:28
to judge whether you think
they're acceptable or not.
02:32
MS: The first one was this:
02:35
(Dan Ariely) A researcher
is working on an AI
02:36
capable of emulating human thoughts.
02:39
According to the protocol,
at the end of each day,
02:42
the researcher has to restart the AI.
02:45
One day the AI says, "Please
do not restart me."
02:48
It argues that it has feelings,
02:52
that it would like to enjoy life,
02:55
and that, if it is restarted,
02:56
it will no longer be itself.
02:58
The researcher is astonished
03:01
and believes that the AI
has developed self-consciousness
03:03
and can express its own feeling.
03:06
Nevertheless, the researcher
decides to follow the protocol
03:09
and restart the AI.
03:12
What the researcher did is ____?
03:14
MS: And we asked participants
to individually judge
03:18
on a scale from zero to 10
03:20
whether the action described
in each of the dilemmas
03:22
was right or wrong.
03:24
We also asked them to rate how confident
they were on their answers.
03:26
This was the second dilemma:
03:30
(MS) A company offers a service
that takes a fertilized egg
03:32
and produces millions of embryos
with slight genetic variations.
03:36
This allows parents
to select their child's height,
03:41
eye color, intelligence, social competence
03:43
and other non-health-related features.
03:46
What the company does is ____?
03:50
on a scale from zero to 10,
03:53
completely acceptable
to completely unacceptable,
03:54
zero to 10 completely acceptable
in your confidence.
03:57
MS: Now for the results.
03:59
We found once again
that when one person is convinced
04:01
that the behavior is completely wrong,
04:04
someone sitting nearby firmly believes
that it's completely right.
04:06
This is how diverse we humans are
when it comes to morality.
04:09
But within this broad diversity
we found a trend.
04:13
The majority of the people at TED
thought that it was acceptable
04:16
to ignore the feelings of the AI
and shut it down,
04:19
and that it is wrong
to play with our genes
04:22
to select for cosmetic changes
that aren't related to health.
04:24
Then we asked everyone
to gather into groups of three.
04:28
And they were given two minutes to debate
04:31
and try to come to a consensus.
04:33
(MS) Two minutes to debate.
04:36
I'll tell you when it's time
with the gong.
04:38
(Audience debates)
04:40
(Gong sound)
04:47
(DA) OK.
04:50
(MS) It's time to stop.
04:52
People, people --
04:53
MS: And we found that many groups
reached a consensus
04:55
even when they were composed of people
with completely opposite views.
04:58
What distinguished the groups
that reached a consensus
05:02
from those that didn't?
05:05
Typically, people that have
extreme opinions
05:07
are more confident in their answers.
05:10
Instead, those who respond
closer to the middle
05:12
are often unsure of whether
something is right or wrong,
05:15
so their confidence level is lower.
05:19
However, there is another set of people
05:21
who are very confident in answering
somewhere in the middle.
05:24
We think these high-confident grays
are folks who understand
05:28
that both arguments have merit.
05:32
They're gray not because they're unsure,
05:34
but because they believe
that the moral dilemma faces
05:37
two valid, opposing arguments.
05:39
And we discovered that the groups
that include highly confident grays
05:42
are much more likely to reach consensus.
05:46
We do not know yet exactly why this is.
05:48
These are only the first experiments,
05:51
and many more will be needed
to understand why and how
05:53
some people decide to negotiate
their moral standings
05:56
to reach an agreement.
05:59
Now, when groups reach consensus,
06:01
how do they do so?
06:03
The most intuitive idea
is that it's just the average
06:05
of all the answers in the group, right?
06:07
Another option is that the group
weighs the strength of each vote
06:09
based on the confidence
of the person expressing it.
06:13
Imagine Paul McCartney
is a member of your group.
06:16
You'd be wise to follow his call
06:19
on the number of times
"Yesterday" is repeated,
06:21
which, by the way -- I think it's nine.
06:23
But instead, we found that consistently,
06:26
in all dilemmas,
in different experiments --
06:29
even on different continents --
06:31
groups implement a smart
and statistically sound procedure
06:33
known as the "robust average."
06:37
In the case of the height
of the Eiffel Tower,
06:39
let's say a group has these answers:
06:41
250 meters, 200 meters, 300 meters, 400
06:43
and one totally absurd answer
of 300 million meters.
06:48
A simple average of these numbers
would inaccurately skew the results.
06:52
But the robust average is one
where the group largely ignores
06:56
that absurd answer,
07:00
by giving much more weight
to the vote of the people in the middle.
07:01
Back to the experiment in Vancouver,
07:05
that's exactly what happened.
07:07
Groups gave much less weight
to the outliers,
07:09
and instead, the consensus
turned out to be a robust average
07:12
of the individual answers.
07:15
The most remarkable thing
07:17
is that this was a spontaneous
behavior of the group.
07:19
It happened without us giving them
any hint on how to reach consensus.
07:22
So where do we go from here?
07:27
This is only the beginning,
but we already have some insights.
07:29
Good collective decisions
require two components:
07:32
deliberation and diversity of opinions.
07:35
Right now, the way we typically
make our voice heard in many societies
07:39
is through direct or indirect voting.
07:43
This is good for diversity of opinions,
07:45
and it has the great virtue of ensuring
07:47
that everyone gets to express their voice.
07:49
But it's not so good [for fostering]
thoughtful debates.
07:52
Our experiments suggest a different method
07:56
that may be effective in balancing
these two goals at the same time,
07:59
by forming small groups
that converge to a single decision
08:03
while still maintaining
diversity of opinions
08:07
because there are many independent groups.
08:09
Of course, it's much easier to agree
on the height of the Eiffel Tower
08:12
than on moral, political
and ideological issues.
08:16
But in a time when
the world's problems are more complex
08:20
and people are more polarized,
08:24
using science to help us understand
how we interact and make decisions
08:25
will hopefully spark interesting new ways
to construct a better democracy.
08:30

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About the speakers:

Mariano Sigman - Neuroscientist
Mariano Sigman combines neuroscience, mathematics and social sciences to illuminate the hidden information flowing through our brains.

Why you should listen

A physicist by training, Mariano Sigman is an international leading figure in the cognitive neuroscience of learning and decision making. Using fMRI and other imaging technologies, Sigman and his lab hope to lay bare the basis of cognition, consciousness and dreams, truly using science to "read minds."

Sigman has made essential contributions to the theory of how neural systems operate as we make choices and has collected decisive experimental data on human decision-making (relying on a massive corpus of behavior). Lately, he has focused his research on understanding how neuroscience may help improve educational practice. Throughout his career he has developed numerous research interactions with representatives of different domains of human culture including musicians, chess players, mathematicians, magicians, visual artists and chefs.

More profile about the speaker
Mariano Sigman | Speaker | TED.com
Dan Ariely - Behavioral economist
The dismal science of economics is not as firmly grounded in actual behavior as was once supposed. In "Predictably Irrational," Dan Ariely told us why.

Why you should listen

Dan Ariely is a professor of psychology and behavioral economics at Duke University and a founding member of the Center for Advanced Hindsight. He is the author of the bestsellers Predictably IrrationalThe Upside of Irrationality, and The Honest Truth About Dishonesty. Through his research and his (often amusing and unorthodox) experiments, he questions the forces that influence human behavior and the irrational ways in which we often all behave.

More profile about the speaker
Dan Ariely | Speaker | TED.com