经济学人下载:武装力量(1)

It goes without saying that to be a marine you have to be tough, both physically and mentally.
不用说，要成为一名海军陆战队员，你必须有强健的身体上和坚强的意志。

But which is more important? And, more specifically, which is the bigger obstacle to successful training?
但哪一个更重要？更具体地说，成功训练的最大障碍是什么？

Working on behalf of America's marine corps, Leslie Saxon,
为美国海军陆战队工作的

of the Keck School of Medicine of the University of Southern California, has been trying to find out.
南加州大学凯克医学院的Leslie Saxon一直在努力寻找答案。

The elite of the marine corps is a group called Force Reconnaissance.
海军陆战队的精英组成的部队被称为陆战远征军直属侦察部队。

These troops are employed in special operations, both "green" (in which having had to engage the enemy is deemed a failure)
此类部队会参加特别行动——绿色行动（行动中，若出现必须与敌人交战的情况，则任务被视为失败）

and "black" (where such engagement is the whole point).
以及黑色行动（在此行动中，交战是重点）。

Initial training to join the force, open only to those already marines or naval doctors, lasts 25 days.
加入这支部队的最初训练（只对那些已经是海军陆战队员或海军医生开放）要持续25天。

Among other things it requires volunteers to tread water for nearly an hour,
此外，还要求参与者踩水近一小时

to run eight miles (12km) while carrying more than 50lb (about 23kg) of equipment,
负重超过50磅（约23公斤）的设备跑8英里（12公里）

and to swim 100 yards (90 metres) with their hands and feet bound.
并且将双手和双脚绑起来游100码（90米）。

Only half of those who volunteer for this training complete it.
只有一半的参与者完成训练。

Of those who do not, roughly half are failed by the judges for posing a safety risk
没能完成的参与者中，有大概一半的人因为构成安全风险而被裁判判为不合格

or for having a medical problem that stops them completing the course. The other half, though, drop out of their own volition.
或者因为身体上的问题而无法结业。而另一半则是自愿退出。

That high drop-out rate is both expensive and vexing for Force Reconnaissance's recruiters.
如此高的退出率对侦察部队的招聘者而言既费钱又费力。

They therefore turned to Dr Saxon to find out what is happening, so that they can take steps to reduce the losses.
因此，他们求助Saxon博士查明原因，以便采取措施减少损失。

To gather the relevant data she picked 121 trainees and provided each of them with two devices: an iPhone and an Apple Watch
为了收集相关数据，她挑选了121名学员，并为他们每人提供了两套设备：一部苹果手机和一块苹果表

(a wrist band that both tells the time like a conventional watch and watches what the wearer gets up to).
（这款腕带表既能像传统手表那样显示时间，又能观察佩戴者的行为）。

She loaded the phones with an app that asked participants a range of demographic
她给手机安装了一款应用，在培训开始时

and psychological questions at the start of their training.
向参与者询问一系列人口和心理问题。

From the answers to these she generated, for each volunteer,
从这些问题的答案中，她为每个志愿者

scores for the five main personality traits recognised by psychologists—
生成了心理学家认可的五种主要人格特征的得分——

openness, conscientiousness, extroversion, agreeableness and neuroticism—
开朗性、责任性、外向性、亲和性、神经质性——

and also for ego resilience (ability to control anger and to control impulses when stressed),
以及自我适应力（在压力下控制愤怒和冲动的能力），

positive affect (a person's tendency to experience positive emotions when facing challenges),
积极影响（一个人在面对挑战时倾向于体验积极的情绪），

satisfaction with life and level of psychopathy. The watch, meanwhile, monitored the number of steps its wearer took,
和对生活的满意度和精神变态程度的得分。与此同时，这款手表会监测佩戴者的步数，

and kept track of both heart rate and calorie expenditure.
并记录他们的心率和卡路里消耗。