TED2012
Tali Sharot: The optimism bias
Filmed:
Readability: 4.4
2,387,106 views
Are we born to be optimistic, rather than realistic? Tali Sharot shares new research that suggests our brains are wired to look on the bright side -- and how that can be both dangerous and beneficial.
Tali Sharot - Cognitive neuroscientist
Tali Sharot studies why our brains are biased toward optimism. Full bio
Tali Sharot studies why our brains are biased toward optimism. Full bio
Double-click the English transcript below to play the video.
00:16
I'm going to talk to you about optimism --
0
148
3382
00:19
or more precisely, the optimism bias.
1
3530
2483
00:21
It's a cognitive illusion
2
6013
1645
00:23
that we've been studying in my lab for the past few years,
3
7658
2742
00:26
and 80 percent of us have it.
4
10400
1735
00:28
It's our tendency to overestimate
5
12135
2734
00:30
our likelihood of experiencing good events in our lives
6
14869
2923
00:33
and underestimate our likelihood of experiencing bad events.
7
17792
4108
00:37
So we underestimate our likelihood of suffering from cancer,
8
21900
3017
00:40
being in a car accident.
9
24917
1506
00:42
We overestimate our longevity, our career prospects.
10
26423
3186
00:45
In short, we're more optimistic than realistic,
11
29609
3445
00:48
but we are oblivious to the fact.
12
33054
2162
00:51
Take marriage for example.
13
35216
2227
00:53
In the Western world, divorce rates are about 40 percent.
14
37443
3534
00:56
That means that out of five married couples,
15
40977
3469
01:00
two will end up splitting their assets.
16
44446
2721
01:03
But when you ask newlyweds about their own likelihood of divorce,
17
47167
3375
01:06
they estimate it at zero percent.
18
50542
3692
01:10
And even divorce lawyers, who should really know better,
19
54234
3729
01:13
hugely underestimate their own likelihood of divorce.
20
57963
3849
01:17
So it turns out that optimists are not less likely to divorce,
21
61812
3126
01:20
but they are more likely to remarry.
22
64938
2530
01:23
In the words of Samuel Johnson,
23
67468
2303
01:25
"Remarriage is the triumph of hope over experience."
24
69771
3997
01:29
(Laughter)
25
73768
1962
01:31
So if we're married, we're more likely to have kids.
26
75730
4574
01:36
And we all think our kids will be especially talented.
27
80304
3265
01:39
This, by the way, is my two-year-old nephew, Guy.
28
83569
2598
01:42
And I just want to make it absolutely clear
29
86167
2375
01:44
that he's a really bad example of the optimism bias,
30
88542
2771
01:47
because he is in fact uniquely talented.
31
91313
2812
01:50
(Laughter)
32
94125
1435
01:51
And I'm not alone.
33
95560
1607
01:53
Out of four British people, three said
34
97167
2475
01:55
that they were optimistic about the future of their own families.
35
99642
3739
01:59
That's 75 percent.
36
103381
1751
02:01
But only 30 percent said
37
105132
2058
02:03
that they thought families in general
38
107190
2560
02:05
are doing better than a few generations ago.
39
109750
2412
02:08
And this is a really important point,
40
112162
2021
02:10
because we're optimistic about ourselves,
41
114183
1888
02:11
we're optimistic about our kids,
42
116071
1818
02:13
we're optimistic about our families,
43
117889
1788
02:15
but we're not so optimistic about the guy sitting next to us,
44
119677
3183
02:18
and we're somewhat pessimistic
45
122860
2229
02:20
about the fate of our fellow citizens and the fate of our country.
46
125089
3879
02:24
But private optimism about our own personal future
47
128968
4036
02:28
remains persistent.
48
133004
2011
02:30
And it doesn't mean that we think things will magically turn out okay,
49
135015
4066
02:34
but rather that we have the unique ability to make it so.
50
139081
4032
02:39
Now I'm a scientist, I do experiments.
51
143113
2841
02:41
So to show you what I mean,
52
145954
1792
02:43
I'm going to do an experiment here with you.
53
147746
2802
02:46
So I'm going to give you a list of abilities and characteristics,
54
150548
3850
02:50
and I want you to think for each of these abilities
55
154398
2894
02:53
where you stand relative to the rest of the population.
56
157292
4393
02:57
The first one is getting along well with others.
57
161685
3786
03:01
Who here believes they're at the bottom 25 percent?
58
165471
5652
03:07
Okay, that's about 10 people out of 1,500.
59
171123
4322
03:11
Who believes they're at the top 25 percent?
60
175445
4013
03:15
That's most of us here.
61
179458
2710
03:18
Okay, now do the same for your driving ability.
62
182168
4930
03:22
How interesting are you?
63
187098
2583
03:25
How attractive are you?
64
189681
2844
03:28
How honest are you?
65
192525
2954
03:31
And finally, how modest are you?
66
195479
5000
03:36
So most of us put ourselves above average
67
200479
2688
03:39
on most of these abilities.
68
203167
2029
03:41
Now this is statistically impossible.
69
205196
2131
03:43
We can't all be better than everyone else.
70
207327
3229
03:46
(Laughter)
71
210556
1642
03:48
But if we believe we're better than the other guy,
72
212198
2677
03:50
well that means that we're more likely to get that promotion, to remain married,
73
214875
4083
03:54
because we're more social, more interesting.
74
218958
2598
03:57
And it's a global phenomenon.
75
221556
2163
03:59
The optimism bias has been observed
76
223719
2468
04:02
in many different countries --
77
226187
1719
04:03
in Western cultures, in non-Western cultures,
78
227906
3104
04:06
in females and males,
79
231010
1506
04:08
in kids, in the elderly.
80
232516
1724
04:10
It's quite widespread.
81
234240
1783
04:11
But the question is, is it good for us?
82
236023
3500
04:15
So some people say no.
83
239523
2454
04:17
Some people say the secret to happiness
84
241977
2518
04:20
is low expectations.
85
244495
2753
04:23
I think the logic goes something like this:
86
247248
2504
04:25
If we don't expect greatness,
87
249752
2258
04:27
if we don't expect to find love and be healthy and successful,
88
252010
3880
04:31
well we're not going to be disappointed when these things don't happen.
89
255890
3098
04:34
And if we're not disappointed when good things don't happen,
90
258988
3408
04:38
and we're pleasantly surprised when they do,
91
262396
1979
04:40
we will be happy.
92
264375
1781
04:42
So it's a very good theory,
93
266156
1702
04:43
but it turns out to be wrong for three reasons.
94
267858
3027
04:46
Number one: Whatever happens, whether you succeed or you fail,
95
270885
4615
04:51
people with high expectations always feel better.
96
275500
3858
04:55
Because how we feel when we get dumped or win employee of the month
97
279358
3932
04:59
depends on how we interpret that event.
98
283290
3030
05:02
The psychologists Margaret Marshall and John Brown
99
286320
4050
05:06
studied students with high and low expectations.
100
290370
2994
05:09
And they found that when people with high expectations succeed,
101
293364
4184
05:13
they attribute that success to their own traits.
102
297548
2910
05:16
"I'm a genius, therefore I got an A,
103
300458
2196
05:18
therefore I'll get an A again and again in the future."
104
302654
2675
05:21
When they failed, it wasn't because they were dumb,
105
305329
2973
05:24
but because the exam just happened to be unfair.
106
308302
3173
05:27
Next time they will do better.
107
311475
2283
05:29
People with low expectations do the opposite.
108
313758
3077
05:32
So when they failed it was because they were dumb,
109
316835
2832
05:35
and when they succeeded
110
319667
1500
05:37
it was because the exam just happened to be really easy.
111
321167
3317
05:40
Next time reality would catch up with them.
112
324484
2401
05:42
So they felt worse.
113
326885
2073
05:44
Number two: Regardless of the outcome,
114
328958
3240
05:48
the pure act of anticipation makes us happy.
115
332198
4047
05:52
The behavioral economist George Lowenstein
116
336245
3176
05:55
asked students in his university
117
339421
1719
05:57
to imagine getting a passionate kiss from a celebrity, any celebrity.
118
341140
4362
06:01
Then he said, "How much are you willing to pay
119
345502
2885
06:04
to get a kiss from a celebrity
120
348387
1988
06:06
if the kiss was delivered immediately,
121
350375
2227
06:08
in three hours, in 24 hours, in three days,
122
352602
5023
06:13
in one year, in 10 years?
123
357625
2433
06:15
He found that the students were willing to pay the most
124
360058
3130
06:19
not to get a kiss immediately,
125
363188
1999
06:21
but to get a kiss in three days.
126
365187
2980
06:24
They were willing to pay extra in order to wait.
127
368167
4247
06:28
Now they weren't willing to wait a year or 10 years;
128
372414
3003
06:31
no one wants an aging celebrity.
129
375417
1421
06:32
But three days seemed to be the optimum amount.
130
376838
4789
06:37
So why is that?
131
381627
2303
06:39
Well if you get the kiss now, it's over and done with.
132
383930
3424
06:43
But if you get the kiss in three days,
133
387354
1950
06:45
well that's three days of jittery anticipation, the thrill of the wait.
134
389304
4154
06:49
The students wanted that time
135
393458
1869
06:51
to imagine where is it going to happen,
136
395327
2381
06:53
how is it going to happen.
137
397708
1629
06:55
Anticipation made them happy.
138
399337
2211
06:57
This is, by the way, why people prefer Friday to Sunday.
139
401548
3869
07:01
It's a really curious fact,
140
405417
2083
07:03
because Friday is a day of work and Sunday is a day of pleasure,
141
407500
3417
07:06
so you'd assume that people will prefer Sunday,
142
410917
2904
07:09
but they don't.
143
413821
1721
07:11
It's not because they really, really like being in the office
144
415542
2875
07:14
and they can't stand strolling in the park
145
418417
1967
07:16
or having a lazy brunch.
146
420384
1661
07:17
We know that, because when you ask people
147
422045
2136
07:20
about their ultimate favorite day of the week,
148
424181
2704
07:22
surprise, surprise, Saturday comes in at first,
149
426885
2820
07:25
then Friday, then Sunday.
150
429705
2920
07:28
People prefer Friday
151
432625
1869
07:30
because Friday brings with it the anticipation of the weekend ahead,
152
434494
3964
07:34
all the plans that you have.
153
438458
1917
07:36
On Sunday, the only thing you can look forward to
154
440375
2704
07:38
is the work week.
155
443079
2254
07:41
So optimists are people who expect more kisses in their future,
156
445333
4877
07:46
more strolls in the park.
157
450210
1921
07:48
And that anticipation enhances their wellbeing.
158
452131
3907
07:51
In fact, without the optimism bias,
159
456038
2964
07:54
we would all be slightly depressed.
160
459002
2750
07:57
People with mild depression,
161
461752
2267
07:59
they don't have a bias when they look into the future.
162
464019
2979
08:02
They're actually more realistic than healthy individuals.
163
466998
4222
08:07
But individuals with severe depression,
164
471220
2101
08:09
they have a pessimistic bias.
165
473321
1829
08:11
So they tend to expect the future
166
475150
2463
08:13
to be worse than it ends up being.
167
477613
2477
08:15
So optimism changes subjective reality.
168
480090
3243
08:19
The way we expect the world to be changes the way we see it.
169
483333
3750
08:22
But it also changes objective reality.
170
487083
3242
08:26
It acts as a self-fulfilling prophecy.
171
490325
2727
08:28
And that is the third reason
172
493052
2068
08:31
why lowering your expectations will not make you happy.
173
495120
3180
08:34
Controlled experiments have shown
174
498300
1835
08:36
that optimism is not only related to success,
175
500135
2917
08:38
it leads to success.
176
503052
1807
08:40
Optimism leads to success in academia and sports and politics.
177
504859
4870
08:45
And maybe the most surprising benefit of optimism is health.
178
509729
4475
08:50
If we expect the future to be bright,
179
514204
3325
08:53
stress and anxiety are reduced.
180
517529
2740
08:56
So all in all, optimism has lots of benefits.
181
520269
4220
09:00
But the question that was really confusing to me was,
182
524489
3011
09:03
how do we maintain optimism in the face of reality?
183
527500
4669
09:08
As an neuroscientist, this was especially confusing,
184
532169
3018
09:11
because according to all the theories out there,
185
535187
2896
09:13
when your expectations are not met, you should alter them.
186
538083
4188
09:18
But this is not what we find.
187
542271
1552
09:19
We asked people to come into our lab
188
543823
3483
09:23
in order to try and figure out what was going on.
189
547306
2810
09:26
We asked them to estimate their likelihood
190
550116
2547
09:28
of experiencing different terrible events in their lives.
191
552663
2504
09:31
So, for example, what is your likelihood of suffering from cancer?
192
555167
4375
09:35
And then we told them the average likelihood
193
559542
2352
09:37
of someone like them to suffer these misfortunes.
194
561894
2981
09:40
So cancer, for example, is about 30 percent.
195
564875
3565
09:44
And then we asked them again,
196
568440
2935
09:47
"How likely are you to suffer from cancer?"
197
571375
2875
09:50
What we wanted to know was
198
574250
2248
09:52
whether people will take the information that we gave them
199
576498
2669
09:55
to change their beliefs.
200
579167
2131
09:57
And indeed they did --
201
581298
2369
09:59
but mostly when the information we gave them
202
583667
2581
10:02
was better than what they expected.
203
586248
2831
10:04
So for example,
204
589079
1361
10:06
if someone said, "My likelihood of suffering from cancer
205
590440
2910
10:09
is about 50 percent,"
206
593350
2381
10:11
and we said, "Hey, good news.
207
595731
2521
10:14
The average likelihood is only 30 percent,"
208
598252
2581
10:16
the next time around they would say,
209
600833
2046
10:18
"Well maybe my likelihood is about 35 percent."
210
602879
2715
10:21
So they learned quickly and efficiently.
211
605594
2636
10:24
But if someone started off saying,
212
608230
2550
10:26
"My average likelihood of suffering from cancer is about 10 percent,"
213
610780
3403
10:30
and we said, "Hey, bad news.
214
614183
2692
10:32
The average likelihood is about 30 percent,"
215
616875
3073
10:35
the next time around they would say,
216
619948
2058
10:37
"Yep. Still think it's about 11 percent."
217
622006
3119
10:41
(Laughter)
218
625125
1690
10:42
So it's not that they didn't learn at all -- they did --
219
626815
3319
10:46
but much, much less than when we gave them
220
630134
2336
10:48
positive information about the future.
221
632470
2473
10:50
And it's not that they didn't remember the numbers that we gave them;
222
634943
3034
10:53
everyone remembers that the average likelihood of cancer
223
637977
3073
10:56
is about 30 percent
224
641050
1500
10:58
and the average likelihood of divorce is about 40 percent.
225
642550
2779
11:01
But they didn't think that those numbers were related to them.
226
645329
4631
11:05
What this means is that warning signs such as these
227
649960
4148
11:10
may only have limited impact.
228
654108
2892
11:12
Yes, smoking kills, but mostly it kills the other guy.
229
657000
4159
11:17
What I wanted to know was
230
661159
1883
11:18
what was going on inside the human brain
231
663042
2860
11:21
that prevented us from taking these warning signs personally.
232
665902
4094
11:25
But at the same time,
233
669996
1487
11:27
when we hear that the housing market is hopeful,
234
671483
1978
11:29
we think, "Oh, my house is definitely going to double in price."
235
673461
4116
11:33
To try and figure that out,
236
677577
2085
11:35
I asked the participants in the experiment
237
679662
2473
11:38
to lie in a brain imaging scanner.
238
682135
2161
11:40
It looks like this.
239
684296
1527
11:41
And using a method called functional MRI,
240
685823
3031
11:44
we were able to identify regions in the brain
241
688854
3606
11:48
that were responding to positive information.
242
692460
2817
11:51
One of these regions is called the left inferior frontal gyrus.
243
695277
3579
11:54
So if someone said, "My likelihood of suffering from cancer is 50 percent,"
244
698856
3788
11:58
and we said, "Hey, good news.
245
702644
1856
12:00
Average likelihood is 30 percent,"
246
704500
2290
12:02
the left inferior frontal gyrus would respond fiercely.
247
706790
3572
12:06
And it didn't matter if you're an extreme optimist, a mild optimist
248
710362
4732
12:10
or slightly pessimistic,
249
715094
1821
12:12
everyone's left inferior frontal gyrus
250
716915
2585
12:15
was functioning perfectly well,
251
719500
1844
12:17
whether you're Barack Obama or Woody Allen.
252
721344
2906
12:20
On the other side of the brain,
253
724250
1644
12:21
the right inferior frontal gyrus was responding to bad news.
254
725894
4786
12:26
And here's the thing: it wasn't doing a very good job.
255
730680
3726
12:30
The more optimistic you were,
256
734406
2015
12:32
the less likely this region was
257
736421
2337
12:34
to respond to unexpected negative information.
258
738758
2982
12:37
And if your brain is failing
259
741740
3058
12:40
at integrating bad news about the future,
260
744798
3225
12:43
you will constantly leave your rose-tinted spectacles on.
261
748023
4623
12:48
So we wanted to know, could we change this?
262
752646
4969
12:53
Could we alter people's optimism bias
263
757615
3443
12:56
by interfering with the brain activity in these regions?
264
761058
3932
13:00
And there's a way for us to do that.
265
764990
2595
13:03
This is my collaborator Ryota Kanai.
266
767585
2627
13:06
And what he's doing is he's passing a small magnetic pulse
267
770212
3955
13:10
through the skull of the participant in our study
268
774167
2119
13:12
into their inferior frontal gyrus.
269
776286
2245
13:14
And by doing that,
270
778531
1927
13:16
he's interfering with the activity of this brain region
271
780458
2904
13:19
for about half an hour.
272
783362
1215
13:20
After that everything goes back to normal, I assure you.
273
784577
2921
13:23
(Laughter)
274
787498
1993
13:25
So let's see what happens.
275
789491
3154
13:28
First of all, I'm going to show you
276
792645
2097
13:30
the average amount of bias that we see.
277
794742
2704
13:33
So if I was to test all of you now,
278
797446
2823
13:36
this is the amount that you would learn
279
800269
1794
13:37
more from good news relative to bad news.
280
802063
3120
13:41
Now we interfere with the region
281
805183
2484
13:43
that we found to integrate negative information in this task,
282
807667
4467
13:48
and the optimism bias grew even larger.
283
812134
3564
13:51
We made people more biased in the way that they process information.
284
815698
5470
13:57
Then we interfered with the brain region
285
821168
2897
13:59
that we found to integrate good news in this task,
286
824065
3518
14:03
and the optimism bias disappeared.
287
827583
4471
14:07
We were quite amazed by these results
288
832054
2008
14:09
because we were able to eliminate
289
834062
2192
14:12
a deep-rooted bias in humans.
290
836254
3196
14:15
And at this point we stopped and we asked ourselves,
291
839450
4773
14:20
would we want to shatter the optimism illusion into tiny little bits?
292
844223
5102
14:25
If we could do that, would we want to take people's optimism bias away?
293
849325
5044
14:30
Well I've already told you about all of the benefits of the optimism bias,
294
854369
4600
14:34
which probably makes you want to hold onto it for dear life.
295
858969
4321
14:39
But there are, of course, pitfalls,
296
863290
2085
14:41
and it would be really foolish of us to ignore them.
297
865375
3120
14:44
Take for example this email I recieved
298
868495
3546
14:47
from a firefighter here in California.
299
872041
2694
14:50
He says, "Fatality investigations for firefighters
300
874735
3304
14:53
often include 'We didn't think the fire was going to do that,'
301
878039
4142
14:58
even when all of the available information
302
882181
2302
15:00
was there to make safe decisions."
303
884483
2255
15:02
This captain is going to use our findings on the optimism bias
304
886738
3874
15:06
to try to explain to the firefighters
305
890612
2192
15:08
why they think the way they do,
306
892804
2209
15:10
to make them acutely aware of this very optimistic bias in humans.
307
895013
7126
15:18
So unrealistic optimism can lead to risky behavior,
308
902139
5119
15:23
to financial collapse, to faulty planning.
309
907258
3638
15:26
The British government, for example,
310
910896
2138
15:28
has acknowledged that the optimism bias
311
913034
2674
15:31
can make individuals more likely
312
915708
3287
15:34
to underestimate the costs and durations of projects.
313
918995
4026
15:38
So they have adjusted the 2012 Olympic budget
314
923021
4254
15:43
for the optimism bias.
315
927275
2111
15:45
My friend who's getting married in a few weeks
316
929386
2187
15:47
has done the same for his wedding budget.
317
931573
2434
15:49
And by the way, when I asked him about his own likelihood of divorce,
318
934007
3062
15:52
he said he was quite sure it was zero percent.
319
937069
3560
15:56
So what we would really like to do,
320
940629
2417
15:58
is we would like to protect ourselves from the dangers of optimism,
321
943046
4161
16:03
but at the same time remain hopeful,
322
947207
3228
16:06
benefiting from the many fruits of optimism.
323
950435
2844
16:09
And I believe there's a way for us to do that.
324
953279
2804
16:11
The key here really is knowledge.
325
956083
2060
16:14
We're not born with an innate understanding of our biases.
326
958143
3311
16:17
These have to be identified by scientific investigation.
327
961454
3841
16:21
But the good news is that becoming aware of the optimism bias
328
965295
4184
16:25
does not shatter the illusion.
329
969479
1775
16:27
It's like visual illusions,
330
971254
1548
16:28
in which understanding them does not make them go away.
331
972802
3490
16:32
And this is good because it means
332
976292
2237
16:34
we should be able to strike a balance,
333
978529
2473
16:36
to come up with plans and rules
334
981002
2427
16:39
to protect ourselves from unrealistic optimism,
335
983429
2783
16:42
but at the same time remain hopeful.
336
986212
3152
16:45
I think this cartoon portrays it nicely.
337
989364
3424
16:48
Because if you're one of these pessimistic penguins up there
338
992788
3526
16:52
who just does not believe they can fly,
339
996314
2119
16:54
you certainly never will.
340
998433
2359
16:56
Because to make any kind of progress,
341
1000792
1831
16:58
we need to be able to imagine a different reality,
342
1002623
2350
17:00
and then we need to believe that that reality is possible.
343
1004973
3731
17:04
But if you are an extreme optimistic penguin
344
1008714
3524
17:08
who just jumps down blindly hoping for the best,
345
1012238
2762
17:10
you might find yourself in a bit of a mess when you hit the ground.
346
1015000
4781
17:15
But if you're an optimistic penguin
347
1019781
1889
17:17
who believes they can fly,
348
1021670
1796
17:19
but then adjusts a parachute to your back
349
1023466
2663
17:22
just in case things don't work out exactly as you had planned,
350
1026129
3017
17:25
you will soar like an eagle,
351
1029146
1863
17:26
even if you're just a penguin.
352
1031009
3049
17:29
Thank you.
353
1034058
1762
17:31
(Applause)
354
1035820
2936
ABOUT THE SPEAKER
Tali Sharot - Cognitive neuroscientistTali Sharot studies why our brains are biased toward optimism.
Why you should listen
Optimism bias is the belief that the future will be better, much better, than the past or present. And most of us display this bias. Neuroscientist Tali Sharot wants to know why: What is it about our brains that makes us overestimate the positive? She explores the question in her book The Optimism Bias: A Tour of the Irrationally Positive Brain.
In the book (and a 2011 TIME magazine cover story), she reviewed findings from both social science and neuroscience that point to an interesting conclusion: "our brains aren't just stamped by the past. They are constantly being shaped by the future." In her own work, she's interested in how our natural optimism actually shapes what we remember, and her interesting range of papers encompasses behavioral research (how likely we are to misremember major events) as well as medical findings -- like searching for the places in the brain where optimism lives. Sharot is a faculty member of the Department of Cognitive, Perceptual and Brain Sciences at University College London.
Tali Sharot | Speaker | TED.com