Manhattan memory project: How 9/11 changed our brains

Manhattan memory project: How 9/11 changed our brains

 You'll probably remember exactly where you were and what you were doing when you first learned that passenger jets had crashed into the World Trade Center. People tend to form exceptionally vivid memories of highly consequential¹ news, and it doesn't get much bigger than 9/11.

Recollections of that day have given researchers a unique window into how the brain forms memories of shocking events. "It's as if a flashbulb goes off and you take a mental picture of your surroundings," says psychologist William Hirst of the New York School for Social Research.

Flashbulb memories, as they are known, are tricky² to study as people are seldom keen to talk to researchers just after hearing or seeing emotionally charged news. It can also be difficult to know how accurate a person's memory of the event is, since there is usually no way to be sure what actually happened.

Elizabeth Phelps of New York University was in Manhattan on 9/11 and saw the attack. When fellow neuroscientist John Gabrieli called to check on her they "decided³ to put together a consortium of memory researchers, and started collecting data within a week".

Public tragedy

"It struck us that 9/11 was probably one of the best examples of a public tragedy that we could use [to study flashbulb memory]," says Hirst.

The study involved surveying over 3000 Americans from seven different cities, including New York, within two to three days of the attack. Participants were asked to note all the details they could remember of the day itself, their personal circumstances at the time, and how they felt. To find out whether the memories formed would be lasting⁴ ones, the group sent out the same survey to the same participants again 11 months later, and once more 35 months after the attacks.

"People were about 60 per cent right about the details of the event after about a year, and this dropped to 50 per cent after three years," suggesting flashbulb memories are no more accurate than other types of memory, says Phelps. But that didn't affect how vividly⁵ people recalled the day, or how much faith they had in the details of their memories .

But evidence that flashbulb memories might be processed differently to other types of memory was provided by Patrick Davidson's team at the University of Arizona in Tucson, who investigated whether memories for 9/11 degraded in the same way as other memories in older individuals. The group found that while older people with frontal lobe⁶ damage struggled to remember other personal events, they remembered 9/11 as well as young people, suggesting that flashbulb memories might be uniquely impervious⁷ to ageing .

Malleable⁸ memories

These vivid yet inaccurate⁹ memories might well be the brain's best way of dealing¹⁰ with an emotional, life-changing event, says Phelps. Keeping the memory malleable to some extent can have benefits: "If a group arrives at a memory of shared suffering, it could be a positive thing in terms of group spirit and identity, and could pull the community together," says Hirst.

When Phelps reassessed the survey responses recently, she found that people's memories of where they were on 9/11 have stayed consistent, though how they felt is harder to recall. "People tended to have around 80 per cent accuracy in their place memories, but were only 40 per cent accurate at remembering their emotions," says Phelps, who is writing up the finding. A weak emotional memory could also be useful in getting over tragic¹¹ events.

In another study three years after the attacks, Phelps used functional¹² MRI to monitor the brain activity of New Yorkers as they recalled the events of 9/11, along with other personal, life-changing events from the same period. She found that when recalling 9/11 those who had been within 4 kilometres of the Twin Towers during the attack had relatively¹³ higher activity in the amygdala – a region of the brain involved in emotion – than those who had been further away, suggesting that flashbulb memories may be encoded differently in the brains of those closest to the attack .

This theory has been backed by surveys by Olivier Luminet and Antonietta Curci, at the Catholic University of Louvain in Belgium. The pair found that, while both US and non-US citizens developed flashbulb memories of the event, they appeared to have done so in different ways. US citizens who had rated the attack as more surprising had more consistent memories, but non-US citizens were better able to remember the event when they were more emotionally affected¹⁴ by it .

A decade on, can you be sure what you were doing when you heard of the attacks? Phelps and Hirst are conducting a 10-year follow-up of their original participants that will, for the first time, show how flashbulb memories survive in the long term.

1 consequential   

adj.作为结果的，间接的；重要的

参考例句：

• She was injured and suffered a consequential loss of earnings.她受了伤因而收入受损。
• This new transformation is at least as consequential as that one was.这一新的转变至少和那次一样重要。

2 tricky   

adj.狡猾的，奸诈的；(工作等)棘手的，微妙的

参考例句：

• I'm in a rather tricky position.Can you help me out?我的处境很棘手，你能帮我吗？
• He avoided this tricky question and talked in generalities.他回避了这个非常微妙的问题，只做了个笼统的表述。

3 decided   

adj.决定了的，坚决的；明显的，明确的

参考例句：

• This gave them a decided advantage over their opponents.这使他们比对手具有明显的优势。
• There is a decided difference between British and Chinese way of greeting.英国人和中国人打招呼的方式有很明显的区别。

4 lasting   

adj.永久的，永恒的；vbl.持续，维持

参考例句：

• The lasting war debased the value of the dollar.持久的战争使美元贬值。
• We hope for a lasting settlement of all these troubles.我们希望这些纠纷能获得永久的解决。

5 vividly   

adv.清楚地，鲜明地，生动地

参考例句：

• The speaker pictured the suffering of the poor vividly.演讲者很生动地描述了穷人的生活。
• The characters in the book are vividly presented.这本书里的人物写得栩栩如生。

6 lobe   

n.耳垂，（肺，肝等的）叶

参考例句：

• Tiny electrical sensors are placed on your scalp and on each ear lobe.小电器传感器放置在您的头皮和对每个耳垂。
• The frontal lobe of the brain is responsible for controlling movement.大脑前叶的功能是控制行动。

7 impervious   

adj.不能渗透的，不能穿过的，不易伤害的

参考例句：

• He was completely impervious to criticism.他对批评毫不在乎。
• This material is impervious to gases and liquids.气体和液体都透不过这种物质。

8 malleable   

adj.(金属)可锻的;有延展性的；(性格)可训练的

参考例句：

• Silver is the most malleable of all metals.银是延展性最好的金属。
• Scientists are finding that the adult human brain is far more malleable than they once thought.科学家发现成人大脑的可塑性远超过他们之前认识到的。

9 inaccurate   

adj.错误的，不正确的，不准确的

参考例句：

• The book is both inaccurate and exaggerated.这本书不但不准确，而且夸大其词。
• She never knows the right time because her watch is inaccurate.她从来不知道准确的时间因为她的表不准。

10 dealing   

n.经商方法，待人态度

参考例句：

• This store has an excellent reputation for fair dealing.该商店因买卖公道而享有极高的声誉。
• His fair dealing earned our confidence.他的诚实的行为获得我们的信任。

11 tragic   

adj.悲剧的，悲剧性的，悲惨的

参考例句：

• The effect of the pollution on the beaches is absolutely tragic.污染海滩后果可悲。
• Charles was a man doomed to tragic issues.查理是个注定不得善终的人。

12 functional   

adj.为实用而设计的，具备功能的，起作用的

参考例句：

• The telephone was out of order,but is functional now.电话刚才坏了，但现在可以用了。
• The furniture is not fancy,just functional.这些家具不是摆着好看的，只是为了实用。

13 relatively   

adv.比较...地，相对地

参考例句：

• The rabbit is a relatively recent introduction in Australia.兔子是相对较新引入澳大利亚的物种。
• The operation was relatively painless.手术相对来说不痛。

14 affected   

adj.不自然的，假装的

参考例句：

• She showed an affected interest in our subject.她假装对我们的课题感到兴趣。
• His manners are affected.他的态度不自然。