The optimism bias | Tali Sharot

551,354 views ・ 2012-05-14

TED


Please double-click on the English subtitles below to play the video.

00:00
Translator: Timothy Covell Reviewer: Morton Bast
0
0
7000
00:15
I'm going to talk to you about optimism --
1
15408
3382
00:18
or more precisely, the optimism bias.
2
18790
2483
00:21
It's a cognitive illusion
3
21273
1645
00:22
that we've been studying in my lab for the past few years,
4
22918
2742
00:25
and 80 percent of us have it.
5
25660
1735
00:27
It's our tendency to overestimate
6
27395
2734
00:30
our likelihood of experiencing good events in our lives
7
30129
2923
00:33
and underestimate our likelihood of experiencing bad events.
8
33052
4108
00:37
So we underestimate our likelihood of suffering from cancer,
9
37160
3017
00:40
being in a car accident.
10
40177
1506
00:41
We overestimate our longevity, our career prospects.
11
41683
3186
00:44
In short, we're more optimistic than realistic,
12
44869
3445
00:48
but we are oblivious to the fact.
13
48314
2162
00:50
Take marriage for example.
14
50476
2227
00:52
In the Western world, divorce rates are about 40 percent.
15
52703
3534
00:56
That means that out of five married couples,
16
56237
3469
00:59
two will end up splitting their assets.
17
59706
2721
01:02
But when you ask newlyweds about their own likelihood of divorce,
18
62427
3375
01:05
they estimate it at zero percent.
19
65802
3692
01:09
And even divorce lawyers, who should really know better,
20
69494
3729
01:13
hugely underestimate their own likelihood of divorce.
21
73223
3849
01:17
So it turns out that optimists are not less likely to divorce,
22
77072
3126
01:20
but they are more likely to remarry.
23
80198
2530
01:22
In the words of Samuel Johnson,
24
82728
2303
01:25
"Remarriage is the triumph of hope over experience."
25
85031
3997
01:29
(Laughter)
26
89028
1962
01:30
So if we're married, we're more likely to have kids.
27
90990
4574
01:35
And we all think our kids will be especially talented.
28
95564
3265
01:38
This, by the way, is my two-year-old nephew, Guy.
29
98829
2598
01:41
And I just want to make it absolutely clear
30
101427
2375
01:43
that he's a really bad example of the optimism bias,
31
103802
2771
01:46
because he is in fact uniquely talented.
32
106573
2812
01:49
(Laughter)
33
109385
1435
01:50
And I'm not alone.
34
110820
1607
01:52
Out of four British people, three said
35
112427
2475
01:54
that they were optimistic about the future of their own families.
36
114902
3739
01:58
That's 75 percent.
37
118641
1751
02:00
But only 30 percent said
38
120392
2058
02:02
that they thought families in general
39
122450
2560
02:05
are doing better than a few generations ago.
40
125010
2412
02:07
And this is a really important point,
41
127422
2021
02:09
because we're optimistic about ourselves,
42
129443
1888
02:11
we're optimistic about our kids,
43
131331
1818
02:13
we're optimistic about our families,
44
133149
1788
02:14
but we're not so optimistic about the guy sitting next to us,
45
134937
3183
02:18
and we're somewhat pessimistic
46
138120
2229
02:20
about the fate of our fellow citizens and the fate of our country.
47
140349
3879
02:24
But private optimism about our own personal future
48
144228
4036
02:28
remains persistent.
49
148264
2011
02:30
And it doesn't mean that we think things will magically turn out okay,
50
150275
4066
02:34
but rather that we have the unique ability to make it so.
51
154341
4032
02:38
Now I'm a scientist, I do experiments.
52
158373
2841
02:41
So to show you what I mean,
53
161214
1792
02:43
I'm going to do an experiment here with you.
54
163006
2802
02:45
So I'm going to give you a list of abilities and characteristics,
55
165808
3850
02:49
and I want you to think for each of these abilities
56
169658
2894
02:52
where you stand relative to the rest of the population.
57
172552
4393
02:56
The first one is getting along well with others.
58
176945
3786
03:00
Who here believes they're at the bottom 25 percent?
59
180731
5652
03:06
Okay, that's about 10 people out of 1,500.
60
186383
4322
03:10
Who believes they're at the top 25 percent?
61
190705
4013
03:14
That's most of us here.
62
194718
2710
03:17
Okay, now do the same for your driving ability.
63
197428
4930
03:22
How interesting are you?
64
202358
2583
03:24
How attractive are you?
65
204941
2844
03:27
How honest are you?
66
207785
2954
03:30
And finally, how modest are you?
67
210739
5000
03:35
So most of us put ourselves above average
68
215739
2688
03:38
on most of these abilities.
69
218427
2029
03:40
Now this is statistically impossible.
70
220456
2131
03:42
We can't all be better than everyone else.
71
222587
3229
03:45
(Laughter)
72
225816
1642
03:47
But if we believe we're better than the other guy,
73
227458
2677
03:50
well that means that we're more likely to get that promotion, to remain married,
74
230135
4083
03:54
because we're more social, more interesting.
75
234218
2598
03:56
And it's a global phenomenon.
76
236816
2163
03:58
The optimism bias has been observed
77
238979
2468
04:01
in many different countries --
78
241447
1719
04:03
in Western cultures, in non-Western cultures,
79
243166
3104
04:06
in females and males,
80
246270
1506
04:07
in kids, in the elderly.
81
247776
1724
04:09
It's quite widespread.
82
249500
1783
04:11
But the question is, is it good for us?
83
251283
3500
04:14
So some people say no.
84
254783
2454
04:17
Some people say the secret to happiness
85
257237
2518
04:19
is low expectations.
86
259755
2753
04:22
I think the logic goes something like this:
87
262508
2504
04:25
If we don't expect greatness,
88
265012
2258
04:27
if we don't expect to find love and be healthy and successful,
89
267270
3880
04:31
well we're not going to be disappointed when these things don't happen.
90
271150
3098
04:34
And if we're not disappointed when good things don't happen,
91
274248
3408
04:37
and we're pleasantly surprised when they do,
92
277656
1979
04:39
we will be happy.
93
279635
1781
04:41
So it's a very good theory,
94
281416
1702
04:43
but it turns out to be wrong for three reasons.
95
283118
3027
04:46
Number one: Whatever happens, whether you succeed or you fail,
96
286145
4615
04:50
people with high expectations always feel better.
97
290760
3858
04:54
Because how we feel when we get dumped or win employee of the month
98
294618
3932
04:58
depends on how we interpret that event.
99
298550
3030
05:01
The psychologists Margaret Marshall and John Brown
100
301580
4050
05:05
studied students with high and low expectations.
101
305630
2994
05:08
And they found that when people with high expectations succeed,
102
308624
4184
05:12
they attribute that success to their own traits.
103
312808
2910
05:15
"I'm a genius, therefore I got an A,
104
315718
2196
05:17
therefore I'll get an A again and again in the future."
105
317914
2675
05:20
When they failed, it wasn't because they were dumb,
106
320589
2973
05:23
but because the exam just happened to be unfair.
107
323562
3173
05:26
Next time they will do better.
108
326735
2283
05:29
People with low expectations do the opposite.
109
329018
3077
05:32
So when they failed it was because they were dumb,
110
332095
2832
05:34
and when they succeeded
111
334927
1500
05:36
it was because the exam just happened to be really easy.
112
336427
3317
05:39
Next time reality would catch up with them.
113
339744
2401
05:42
So they felt worse.
114
342145
2073
05:44
Number two: Regardless of the outcome,
115
344218
3240
05:47
the pure act of anticipation makes us happy.
116
347458
4047
05:51
The behavioral economist George Lowenstein
117
351505
3176
05:54
asked students in his university
118
354681
1719
05:56
to imagine getting a passionate kiss from a celebrity, any celebrity.
119
356400
4362
06:00
Then he said, "How much are you willing to pay
120
360762
2885
06:03
to get a kiss from a celebrity
121
363647
1988
06:05
if the kiss was delivered immediately,
122
365635
2227
06:07
in three hours, in 24 hours, in three days,
123
367862
5023
06:12
in one year, in 10 years?
124
372885
2433
06:15
He found that the students were willing to pay the most
125
375318
3130
06:18
not to get a kiss immediately,
126
378448
1999
06:20
but to get a kiss in three days.
127
380447
2980
06:23
They were willing to pay extra in order to wait.
128
383427
4247
06:27
Now they weren't willing to wait a year or 10 years;
129
387674
3003
06:30
no one wants an aging celebrity.
130
390677
1421
06:32
But three days seemed to be the optimum amount.
131
392098
4789
06:36
So why is that?
132
396887
2303
06:39
Well if you get the kiss now, it's over and done with.
133
399190
3424
06:42
But if you get the kiss in three days,
134
402614
1950
06:44
well that's three days of jittery anticipation, the thrill of the wait.
135
404564
4154
06:48
The students wanted that time
136
408718
1869
06:50
to imagine where is it going to happen,
137
410587
2381
06:52
how is it going to happen.
138
412968
1629
06:54
Anticipation made them happy.
139
414597
2211
06:56
This is, by the way, why people prefer Friday to Sunday.
140
416808
3869
07:00
It's a really curious fact,
141
420677
2083
07:02
because Friday is a day of work and Sunday is a day of pleasure,
142
422760
3417
07:06
so you'd assume that people will prefer Sunday,
143
426177
2904
07:09
but they don't.
144
429081
1721
07:10
It's not because they really, really like being in the office
145
430802
2875
07:13
and they can't stand strolling in the park
146
433677
1967
07:15
or having a lazy brunch.
147
435644
1661
07:17
We know that, because when you ask people
148
437305
2136
07:19
about their ultimate favorite day of the week,
149
439441
2704
07:22
surprise, surprise, Saturday comes in at first,
150
442145
2820
07:24
then Friday, then Sunday.
151
444965
2920
07:27
People prefer Friday
152
447885
1869
07:29
because Friday brings with it the anticipation of the weekend ahead,
153
449754
3964
07:33
all the plans that you have.
154
453718
1917
07:35
On Sunday, the only thing you can look forward to
155
455635
2704
07:38
is the work week.
156
458339
2254
07:40
So optimists are people who expect more kisses in their future,
157
460593
4877
07:45
more strolls in the park.
158
465470
1921
07:47
And that anticipation enhances their wellbeing.
159
467391
3907
07:51
In fact, without the optimism bias,
160
471298
2964
07:54
we would all be slightly depressed.
161
474262
2750
07:57
People with mild depression,
162
477012
2267
07:59
they don't have a bias when they look into the future.
163
479279
2979
08:02
They're actually more realistic than healthy individuals.
164
482258
4222
08:06
But individuals with severe depression,
165
486480
2101
08:08
they have a pessimistic bias.
166
488581
1829
08:10
So they tend to expect the future
167
490410
2463
08:12
to be worse than it ends up being.
168
492873
2477
08:15
So optimism changes subjective reality.
169
495350
3243
08:18
The way we expect the world to be changes the way we see it.
170
498593
3750
08:22
But it also changes objective reality.
171
502343
3242
08:25
It acts as a self-fulfilling prophecy.
172
505585
2727
08:28
And that is the third reason
173
508312
2068
08:30
why lowering your expectations will not make you happy.
174
510380
3180
08:33
Controlled experiments have shown
175
513560
1835
08:35
that optimism is not only related to success,
176
515395
2917
08:38
it leads to success.
177
518312
1807
08:40
Optimism leads to success in academia and sports and politics.
178
520119
4870
08:44
And maybe the most surprising benefit of optimism is health.
179
524989
4475
08:49
If we expect the future to be bright,
180
529464
3325
08:52
stress and anxiety are reduced.
181
532789
2740
08:55
So all in all, optimism has lots of benefits.
182
535529
4220
08:59
But the question that was really confusing to me was,
183
539749
3011
09:02
how do we maintain optimism in the face of reality?
184
542760
4669
09:07
As an neuroscientist, this was especially confusing,
185
547429
3018
09:10
because according to all the theories out there,
186
550447
2896
09:13
when your expectations are not met, you should alter them.
187
553343
4188
09:17
But this is not what we find.
188
557531
1552
09:19
We asked people to come into our lab
189
559083
3483
09:22
in order to try and figure out what was going on.
190
562566
2810
09:25
We asked them to estimate their likelihood
191
565376
2547
09:27
of experiencing different terrible events in their lives.
192
567923
2504
09:30
So, for example, what is your likelihood of suffering from cancer?
193
570427
4375
09:34
And then we told them the average likelihood
194
574802
2352
09:37
of someone like them to suffer these misfortunes.
195
577154
2981
09:40
So cancer, for example, is about 30 percent.
196
580135
3565
09:43
And then we asked them again,
197
583700
2935
09:46
"How likely are you to suffer from cancer?"
198
586635
2875
09:49
What we wanted to know was
199
589510
2248
09:51
whether people will take the information that we gave them
200
591758
2669
09:54
to change their beliefs.
201
594427
2131
09:56
And indeed they did --
202
596558
2369
09:58
but mostly when the information we gave them
203
598927
2581
10:01
was better than what they expected.
204
601508
2831
10:04
So for example,
205
604339
1361
10:05
if someone said, "My likelihood of suffering from cancer
206
605700
2910
10:08
is about 50 percent,"
207
608610
2381
10:10
and we said, "Hey, good news.
208
610991
2521
10:13
The average likelihood is only 30 percent,"
209
613512
2581
10:16
the next time around they would say,
210
616093
2046
10:18
"Well maybe my likelihood is about 35 percent."
211
618139
2715
10:20
So they learned quickly and efficiently.
212
620854
2636
10:23
But if someone started off saying,
213
623490
2550
10:26
"My average likelihood of suffering from cancer is about 10 percent,"
214
626040
3403
10:29
and we said, "Hey, bad news.
215
629443
2692
10:32
The average likelihood is about 30 percent,"
216
632135
3073
10:35
the next time around they would say,
217
635208
2058
10:37
"Yep. Still think it's about 11 percent."
218
637266
3119
10:40
(Laughter)
219
640385
1690
10:42
So it's not that they didn't learn at all -- they did --
220
642075
3319
10:45
but much, much less than when we gave them
221
645394
2336
10:47
positive information about the future.
222
647730
2473
10:50
And it's not that they didn't remember the numbers that we gave them;
223
650203
3034
10:53
everyone remembers that the average likelihood of cancer
224
653237
3073
10:56
is about 30 percent
225
656310
1500
10:57
and the average likelihood of divorce is about 40 percent.
226
657810
2779
11:00
But they didn't think that those numbers were related to them.
227
660589
4631
11:05
What this means is that warning signs such as these
228
665220
4148
11:09
may only have limited impact.
229
669368
2892
11:12
Yes, smoking kills, but mostly it kills the other guy.
230
672260
4159
11:16
What I wanted to know was
231
676419
1883
11:18
what was going on inside the human brain
232
678302
2860
11:21
that prevented us from taking these warning signs personally.
233
681162
4094
11:25
But at the same time,
234
685256
1487
11:26
when we hear that the housing market is hopeful,
235
686743
1978
11:28
we think, "Oh, my house is definitely going to double in price."
236
688721
4116
11:32
To try and figure that out,
237
692837
2085
11:34
I asked the participants in the experiment
238
694922
2473
11:37
to lie in a brain imaging scanner.
239
697395
2161
11:39
It looks like this.
240
699556
1527
11:41
And using a method called functional MRI,
241
701083
3031
11:44
we were able to identify regions in the brain
242
704114
3606
11:47
that were responding to positive information.
243
707720
2817
11:50
One of these regions is called the left inferior frontal gyrus.
244
710537
3579
11:54
So if someone said, "My likelihood of suffering from cancer is 50 percent,"
245
714116
3788
11:57
and we said, "Hey, good news.
246
717904
1856
11:59
Average likelihood is 30 percent,"
247
719760
2290
12:02
the left inferior frontal gyrus would respond fiercely.
248
722050
3572
12:05
And it didn't matter if you're an extreme optimist, a mild optimist
249
725622
4732
12:10
or slightly pessimistic,
250
730354
1821
12:12
everyone's left inferior frontal gyrus
251
732175
2585
12:14
was functioning perfectly well,
252
734760
1844
12:16
whether you're Barack Obama or Woody Allen.
253
736604
2906
12:19
On the other side of the brain,
254
739510
1644
12:21
the right inferior frontal gyrus was responding to bad news.
255
741154
4786
12:25
And here's the thing: it wasn't doing a very good job.
256
745940
3726
12:29
The more optimistic you were,
257
749666
2015
12:31
the less likely this region was
258
751681
2337
12:34
to respond to unexpected negative information.
259
754018
2982
12:37
And if your brain is failing
260
757000
3058
12:40
at integrating bad news about the future,
261
760058
3225
12:43
you will constantly leave your rose-tinted spectacles on.
262
763283
4623
12:47
So we wanted to know, could we change this?
263
767906
4969
12:52
Could we alter people's optimism bias
264
772875
3443
12:56
by interfering with the brain activity in these regions?
265
776318
3932
13:00
And there's a way for us to do that.
266
780250
2595
13:02
This is my collaborator Ryota Kanai.
267
782845
2627
13:05
And what he's doing is he's passing a small magnetic pulse
268
785472
3955
13:09
through the skull of the participant in our study
269
789427
2119
13:11
into their inferior frontal gyrus.
270
791546
2245
13:13
And by doing that,
271
793791
1927
13:15
he's interfering with the activity of this brain region
272
795718
2904
13:18
for about half an hour.
273
798622
1215
13:19
After that everything goes back to normal, I assure you.
274
799837
2921
13:22
(Laughter)
275
802758
1993
13:24
So let's see what happens.
276
804751
3154
13:27
First of all, I'm going to show you
277
807905
2097
13:30
the average amount of bias that we see.
278
810002
2704
13:32
So if I was to test all of you now,
279
812706
2823
13:35
this is the amount that you would learn
280
815529
1794
13:37
more from good news relative to bad news.
281
817323
3120
13:40
Now we interfere with the region
282
820443
2484
13:42
that we found to integrate negative information in this task,
283
822927
4467
13:47
and the optimism bias grew even larger.
284
827394
3564
13:50
We made people more biased in the way that they process information.
285
830958
5470
13:56
Then we interfered with the brain region
286
836428
2897
13:59
that we found to integrate good news in this task,
287
839325
3518
14:02
and the optimism bias disappeared.
288
842843
4471
14:07
We were quite amazed by these results
289
847314
2008
14:09
because we were able to eliminate
290
849322
2192
14:11
a deep-rooted bias in humans.
291
851514
3196
14:14
And at this point we stopped and we asked ourselves,
292
854710
4773
14:19
would we want to shatter the optimism illusion into tiny little bits?
293
859483
5102
14:24
If we could do that, would we want to take people's optimism bias away?
294
864585
5044
14:29
Well I've already told you about all of the benefits of the optimism bias,
295
869629
4600
14:34
which probably makes you want to hold onto it for dear life.
296
874229
4321
14:38
But there are, of course, pitfalls,
297
878550
2085
14:40
and it would be really foolish of us to ignore them.
298
880635
3120
14:43
Take for example this email I recieved
299
883755
3546
14:47
from a firefighter here in California.
300
887301
2694
14:49
He says, "Fatality investigations for firefighters
301
889995
3304
14:53
often include 'We didn't think the fire was going to do that,'
302
893299
4142
14:57
even when all of the available information
303
897441
2302
14:59
was there to make safe decisions."
304
899743
2255
15:01
This captain is going to use our findings on the optimism bias
305
901998
3874
15:05
to try to explain to the firefighters
306
905872
2192
15:08
why they think the way they do,
307
908064
2209
15:10
to make them acutely aware of this very optimistic bias in humans.
308
910273
7126
15:17
So unrealistic optimism can lead to risky behavior,
309
917399
5119
15:22
to financial collapse, to faulty planning.
310
922518
3638
15:26
The British government, for example,
311
926156
2138
15:28
has acknowledged that the optimism bias
312
928294
2674
15:30
can make individuals more likely
313
930968
3287
15:34
to underestimate the costs and durations of projects.
314
934255
4026
15:38
So they have adjusted the 2012 Olympic budget
315
938281
4254
15:42
for the optimism bias.
316
942535
2111
15:44
My friend who's getting married in a few weeks
317
944646
2187
15:46
has done the same for his wedding budget.
318
946833
2434
15:49
And by the way, when I asked him about his own likelihood of divorce,
319
949267
3062
15:52
he said he was quite sure it was zero percent.
320
952329
3560
15:55
So what we would really like to do,
321
955889
2417
15:58
is we would like to protect ourselves from the dangers of optimism,
322
958306
4161
16:02
but at the same time remain hopeful,
323
962467
3228
16:05
benefiting from the many fruits of optimism.
324
965695
2844
16:08
And I believe there's a way for us to do that.
325
968539
2804
16:11
The key here really is knowledge.
326
971343
2060
16:13
We're not born with an innate understanding of our biases.
327
973403
3311
16:16
These have to be identified by scientific investigation.
328
976714
3841
16:20
But the good news is that becoming aware of the optimism bias
329
980555
4184
16:24
does not shatter the illusion.
330
984739
1775
16:26
It's like visual illusions,
331
986514
1548
16:28
in which understanding them does not make them go away.
332
988062
3490
16:31
And this is good because it means
333
991552
2237
16:33
we should be able to strike a balance,
334
993789
2473
16:36
to come up with plans and rules
335
996262
2427
16:38
to protect ourselves from unrealistic optimism,
336
998689
2783
16:41
but at the same time remain hopeful.
337
1001472
3152
16:44
I think this cartoon portrays it nicely.
338
1004624
3424
16:48
Because if you're one of these pessimistic penguins up there
339
1008048
3526
16:51
who just does not believe they can fly,
340
1011574
2119
16:53
you certainly never will.
341
1013693
2359
16:56
Because to make any kind of progress,
342
1016052
1831
16:57
we need to be able to imagine a different reality,
343
1017883
2350
17:00
and then we need to believe that that reality is possible.
344
1020233
3731
17:03
But if you are an extreme optimistic penguin
345
1023974
3524
17:07
who just jumps down blindly hoping for the best,
346
1027498
2762
17:10
you might find yourself in a bit of a mess when you hit the ground.
347
1030260
4781
17:15
But if you're an optimistic penguin
348
1035041
1889
17:16
who believes they can fly,
349
1036930
1796
17:18
but then adjusts a parachute to your back
350
1038726
2663
17:21
just in case things don't work out exactly as you had planned,
351
1041389
3017
17:24
you will soar like an eagle,
352
1044406
1863
17:26
even if you're just a penguin.
353
1046269
3049
17:29
Thank you.
354
1049318
1762
17:31
(Applause)
355
1051080
2936

Original video on YouTube.com
About this website

This site will introduce you to YouTube videos that are useful for learning English. You will see English lessons taught by top-notch teachers from around the world. Double-click on the English subtitles displayed on each video page to play the video from there. The subtitles scroll in sync with the video playback. If you have any comments or requests, please contact us using this contact form.

https://forms.gle/WvT1wiN1qDtmnspy7