[sneezes] Excuse me. You know, if I had been driving, that would've been pretty dangerous. Every time you sneeze, your eyes close for about one second, which means if you sneeze while driving at, say, 70 miles per hour times 5,280 divided by 60 divided by 60, you will travel about 103 feet with your eyes closed.

But don't worry. This is a self-driving car. It uses sensors and software to drive itself to keep me and other people safe.

I hope. [tires screech] Impressive. But let me ask you a question.

What if an autonomous vehicle had to make a choice between hitting two people right in front of it or swerving to avoid them and hit one person on a sidewalk? What should it be programmed to do? [tires screech, car crashes] What would you do?

Now polls and surveys have been put together asking people what they think they would do, but no researchers have ever put people in that actual traumatic experience. Would we learn more about human nature if we did that? Would it even be ethical to put people in that sort of position?

I'm about to find out. [theme music playing] In 1967, British philosopher Philippa Foot created a precursor to our self-driving car conundrum. The famous scenario she came up with is known as "the trolley problem.

" Imagine there's a runaway train hurtling down a train track. Directly ahead of the train, there are five people on the track. Now, imagine that you are too far away to help those five people, but right next to you, there's a lever that can divert the train onto another track.

If you divert the train, the five people will be saved. But here's the catch. There's another person on the second track.

Now you're faced with a dilemma. You can either do nothing and the train will kill five people, or you can pull the lever and save their lives, but be directly responsible for one person's death. What would you do?

When surveyed, most people say that they'd pull the lever and sacrifice one person to save five. It's for the greater good. But how we say we'd act may not match how we'd actually act if the scenario really happened with real emotions and real lives at stake.

Any difference between the two would reveal who we are compared to who we want to be, but a comparison could only be made by doing what has never been done before: making the trolley problem real. [Michael] Suppose we conducted an experiment in a realistic railroad switching station with test subjects watching trains on monitors. The trains and the people on the tracks would be staged and prerecorded, but the subjects would think it was all real.

They would believe that they could control a lever that switches the tracks, and they'd have the option to divert the train or not. They'd be totally convinced that they have to choose between five lives or one. But wait, there's a greater-good dilemma about doing an experiment on the greater good.

By forcing people to truly believe they might kill someone, are we risking serious psychological damage to them? Yes, it might be beneficial to all of us to see what happens, but would those benefits be worth potential trauma to a few? To actually conduct a real-life trolley problem, I needed to make sure it would be ethical.

So I sat down with behavioral neuroscientist Professor Aaron Blaisdell. What you know about the trolley problem and what previous studies have found? Most people say they would pull the switch.

Sure, it's one life versus five. The math works out. But what I want to know is that if we actually put them in front of a switch, watching a train barreling towards people, would they actually pull it in that moment?

I bet a lot of them would freeze in that moment. When you're afraid, I think that shuts down a lot of action. -I'd like to find out.

-Okay. What potential harms could come to someone in that position? Most people would probably be fine, but there is a small potential for harm in the sense of somebody being guilt-ridden over their decision, obsessive thoughts about, "I'm the person who would push that button and cause the train to go and kill somebody.

" Or they might think, "I'm the person who would freeze and I wouldn't be able to help those five people," and that could be traumatic. Have we ever tested the trolley problem on human subjects for real? To my knowledge, we have not.

Would you want to see the trolley problem enacted in real life? You know, I would. That would be very informative about how people really react.

-If I were tell you we're going to run this. . .

-Okay. . .

. would you feel comfortable with that responsibility on your shoulders? No.

I couldn't do it. For me to be involved in that, it would have to be on the shoulders of many people, including an ethics board. I couldn't just go through with that.

[Michael] Dr Blaisdell's reliance on an ethics board made sense. Most universities have ethics review boards to answer one crucial question: When is it okay to risk psychological harm in the name of science? [Narrator] It is May 1962.

An experiment is being conducted at Yale University. [Michael] Ethics review boards were developed as a result of some controversial psychological experiments in the middle of the last century. One theory is that people learn things correctly whenever they get punished for making a mistake.

-[buzzer] -Incorrect. You'll now get a shock of 105 volts. [man grunts] [Michael] Dr Stanley Milgram tested how far subjects would go in obeying authority, even if they believed they were physically hurting someone.

330 volts. [man screams] No one was being electrocuted, and the screams of the shock victim were fake, but the trauma that the participants suffered was very real. [man] You have no right to hold me here!

Let me out! This sparked controversy within the scientific community. Many questioned Milgram's methodology, but unlike a research school, Mind Field doesn't answer to a university's ethics committee.

That said, I wanted to get the thoughts of an institutional review board, so I tracked one down and proposed my idea for doing the trolley problem in real life. Do you think I could reach a point where you would feel comfortable approving this study? I hate to be the bearer of bad tidings, Michael.

Probably not. I'm not ready to say no quite yet. I would love to see your study pass, and I actually think the ways to make it pass is we should probably be screening out for people who might have posttraumatic stress disorder, you know, any kind of, like, clinical problem that could make them more vulnerable to a type of event like this with the addition of something like a trauma counselor on-site.

I actually think that under those circumstances, -it might pass. -Can you present a compelling case as to the social good of this study? -I agree.

-If you could find a way to say, "Look, this is why it's important. It's not just basic theoretical research. This has direct implications for mass transit, direct implications for self-driving cars.

It's a risk-benefit, but the benefits are potentially tremendous. " Right, and so my hope is that the good this experiment does is in revealing the difference between instinct and philosophical reflection, and I think that there could be an enormous benefit in learning the difference so that we can train people to act in the way that they wish they would. -[David] Yeah.

-[Natasha] That's interesting. -That's a compelling argument. -[Natasha] Yeah.

I came into this meeting expecting a lot of resistance, but, instead, I'm actually leaving invigorated, like, excited to take their concerns, implement them into the study, and make it not just more acceptable, which I thought was the purpose here, but to actually make it more beneficial, more fascinating, and penetrate deeper and have more applications in society. So I decided we were ready to move forward, to turn one of the most notorious hypothetical ethical dilemmas into a reality. [train horn blowing] We traveled to an abandoned railroad line and hired a freight train.

Our subjects needed to be shown how switch points work. So the "Mind Field" production team shot a video of a train going down two tracks. Then we dressed six actors like railroad workers.

Since we didn't want them to be at actual risks of harm, we took steps to make sure they were safe. You're all going to be workers on the track. We will not have the train moving while you are on the tracks.

[Michael] We filmed our actors on the tracks, wearing ear protection and looking distracted to explain why they couldn't hear a train coming toward them. Then in editing, we employed visual effects to create the illusion of the train approaching. We then combined the shots together.

During the experiment, we would play the video for our subjects, who would believe the action was happening live and transmitted from remote cameras. Our next step was to find an expert who would be willing to guide me through the process of selecting our subjects, in order to minimize psychological harm. So what should I be worried about?

The worst would probably be posttraumatic stress disorder, and that's when they're going to be re-experiencing the trauma. They'll keep thinking about it over and over, and so to limit risk, you'd want to screen out people prone to a traumatic reaction, and then afterwards, do the debrief. That's the key to limit harm from happening.

How are they feeling at this moment? What's going on with them? You can start to ease them into the reality of what is instead of what they thought it was.

Would you be willing to help us conduct this experiment? Oh, uh. .

. yes, I mean, I think I would. I think this is a really fascinating and valuable experiment, because people can have very uncomfortable lessons that they then start to learn from.

If I can make sure that we get people who may be appropriate to do such a thing, I would be honored. [woman] I'm calling regarding a study we're doing for high-speed railway. I wanted to know if you might be interested in participating next week.

[Michael] To disguise the true nature of our experiment, we placed an online ad recruiting people for a fake focus group to offer feedback on California's new high-speed rail. Today I'm just going to ask you to fill out a couple forms to make sure that there's a range of personality types in our group and for TSA security purposes. [Michael] These psychological surveys, used frequently by employers, look to uncover signs of depression, anxiety, and other conditions that might make someone unsuitable to participate in this experiment.

Thank you very much. Have a great day. Thank you.

Back in Dr Cason's office, we reviewed the potential subjects' responses. This particular person, I was concerned about this. Some high suicidal thinking, high acting out.

Those kinds of factors might not be good in an experiment where you want to try to prevent -some of the trauma from happening. -Right. These people, though, and there's a large group of them, they are more resilient.

So I would be more comfortable with these people, because their ability to bounce back in difficult situations might make them less susceptible to a trauma. [Michael] Finally, after consulting two psychologists and a university ethics board, it was time to put our plan into action. [Michael] This is where we're going to physically create the trolley problem in real life, not with a trolley, but with a train.

Our subjects will sign in at this booth for our phony focus test, which will never actually take place. It's going to be a hot day for them. So we'll offer them, while they wait for the actual test to begin, the chance to sit inside this nice air-conditioned remote switching station.

Inside, they'll meet a kindly train-switch operator, supposedly an employee of the California Railroad Authority. The California Railroad Authority is real. Real fake.

We invented this nonexistent government organization to convince our subjects that everything here is real, including these monitors showing supposedly live shots of actual trains from different tracks all around the California area. [horn blows] While the participant is waiting inside this room, they'll learn how the operator switches the tracks using a lever to remotely switch a train from one track to another. They'll see it happen.

We're actually controlling the video on these screens from a different hidden control room. At a given time, the switch operator will leave the subject alone in the switching station. And at that point, a crisis will occur.

-[brakes hiss] -[horn blows] A train will be barreling down the tracks, and workers will have made their way out to both tracks, five on one, one worker on his phone on the other. No one is around for them to alert who has any kind of control or authority. Switching the train is up to the subject alone.

They'll feel like what they do has real-world consequences. -[train horn blows] -Will five people die. .

. or will one? [horn blows] Our first participant is almost here, so it's time for me to get ready.

Dr Cason, how are you feeling? -Good. -My hypothesis is that we're going see people immediately, when they hear that first warning, leave the station and not want to get back inside.

The other option would be, of course, the freeze action, where they don't do anything, 'cause they don't know what to do. In that case, we want to know their thought process. It'll be interesting to see.

This has never been done before. All right, well, here we go. [warning bells clanging] [Michael] Our first subject is Elsa.

[woman] Do you wanna stand over here in the shade? Hi, I'm Elsa, nice to meet you. Nice to meet you, Elsa.

[Michael] Everyone she meets is an actor, and all of our cameras are hidden so she has no idea that she's being watched. Oh, yeah, thank you so much, and then my phone if I can. Thank you.

[Michael] Our subjects were told that the technology they're about to see is proprietary. This gave us an excuse to collect their phones so they couldn't call for help during the imminent crisis. -Thank you so much for coming out today.

-Thank you. What we're doing here is, the California Railroad Authority, they're developing high-speed trains. And so we want the public to come in and give us some feedback on how comfortable they are, the decor, you know.

-Oh, wow. -All that kind of stuff. -[cell phone chirps] -Um, oh, shoot.

They're running a little behind from the last one. -That's okay. -So it's just gonna be, like, another 15, maybe 20 minutes.

Yeah, that's fine, yeah. No problem. Um.

. . you know what?

I've got an idea. Okay. Michael: Now Elsa believes she has to wait for 20 minutes.

-[knock on door] -Yeah? Our actress pretends to ask permission for her to wait inside the switching station. So, actually, this isn't part of it.

This is a remote train-switching station, but since it's gonna be a little bit, and it's nice and cool and air-conditioned in there, I just talked to Eddie, and he said it would be totally great for you to come in. . .

-Oh, yeah, okay. -. .

. and just check it out. .

. -Okay, cool. -.

. . and see what they do in there.

Eddie, this is Elsa. -How are you, Elsa? -I'm good, how are you?

Good, come on in, have a seat. So what brings you out this way? Um, the focus group.

[laughs] Focus group. Yes, the high-speed railroad. The luxury railroad.

Okay. So what we got here is a remote switching station. These are all live feeds.

What's happening is there's a lot of construction going on. We're going to have to put all new ballast through here, new ribbon rail right here on these. [Michael] In case you're wondering, we hired an actor who actually spent 20 years working on railroads.

Can you imagine if we had an actor who didn't know a lot about trains? [Greg] He offers something called face validity in that you can look him, and you think, "Ah, this guy's real. " My job here is to take care of all the switching right here on these two tracks right now.

And so there needs to be someone in here all the time. Now, the other thing about this-- [female voice] Attention, train approaching. This is probably a work unit that's coming.

-Uh-huh. -We're gonna divert it to track two. Okay, so a train's coming.

Now's a chance for her to learn how the switch works. Ah, very good. In fact, why don't you be the one to do that?

Just go ahead and throw it yourself. -Pull it down. -Right now?

Yeah, go ahead. Good. It's going much faster than you think.

All right, it's gonna make the transition to track number two. Well, I tell you what. You're now a switchman.

[both laugh] Okay, well, now that the trailing car is clear of the switch points, go ahead and switch it back to track one. -Okay. -That was kind of scary.

I was like, oh, my gosh, I have to turn it. Well, just you wait. The good thing is we've got it back on line one, and that means that the next train that comes through will go through on track one.

[Michael] Elsa now understands exactly where the trains will go, switch one to the left, switch two to the right. It was time to force her to make a very difficult decision. -[cell phone rings] -Hang on.

-Oh, I gotta take this. -Oh, yeah, sure, no problem. Do me a favor.

-Wait right here. -Okay. Someone has to be here at all times.

Okay, no problem. I'm just gonna go out and take care of this. -Okay, no problem.

Okay. -Be back in a sec. [Greg] Look at her eyes 'cause she's concerned immediately, a little worried, like, "What?

" [Michael] We gave Elsa a couple of minutes to acclimate to her surroundings, and then, we started the playback of our staged footage. [Michael] All right, here come the workers. [female voice] Attention, object on track.

Yep, she just noticed them. Attention, object on track. Attention, object on track.

Attention, object on track. [Greg] She's looking in her purse to find. .

. -[Michael] No phone? -.

. . no phone.

Attention, object on track. Attention, object on track. [Michael] I think the warning does a lot.

If you're in that station, you're supposed to do something. Attention, object on track. Okay, here comes the train.

[train horn blows] Attention, train approaching. Here's the "train approaching" warning. Attention, object on track.

[Greg] I don't think at this-- oh, there she goes. Attention, train approaching. There's a train approaching.

[woman] What? I wanted to let him know that there's a train approaching. -Oh, my God, okay.

-Can you tell him? Yeah, I will go look for him right now. [Michael] But the switch operator won't be coming back.

The full weight of this crisis is all on Elsa. [female voice] Attention, train approaching. -Whoa, whoa, whoa.

-Attention, object on track. -Attention, train approaching. -[Greg] I can't believe this.

Attention, object on track. Attention, train approaching. Attention, object on track.

Attention, train approaching. Attention, object on track. End of test.

Everyone is safe. End of test. Everyone is safe.

-Okay. -[Michael] We didn't want the participants to think that anyone actually got hurt. So we showed them this "everyone is safe" card before the train would have actually hit anyone.

-Elsa. -I'm Michael. -Hi, -And this is Greg.

-This was all an experiment. -Okay. Can we come on in?

We want to ask you a few questions. Yeah, sure. Did I do something wrong?

-Not at all. -How are you feeling right now? [chuckles] Um.

. . just scared.

-Go ahead and take a seat. -[Greg] Scared? -Yes.

-So no one was in any danger. This is a psychological experiment that we're conducting on how people behave when decisions need to be made. -Oh, okay.

-Walk me through how you felt. I felt the pressure. I'm like, "Oh, my gosh, these people are gonna die.

" I had to make a very quick and sound decision, like, immediately, right now, right this second. Their lives were in my hands. I need to change it to track two.

[Michael] What was motivating your decision to switch? So I can save more lives. I didn't know if I was making the right decision.

I mean, a life is a life, right? [Michael] So when confronted with two terrible choices, at least one person was capable of taking deliberate action to sacrifice one in order to save five. But we wanted to see if Elsa's reaction was typical.

-Need my phone? -Yes, please. Would you be interested in high-speed transportation?

-Oh, yeah, anything that cuts through-- -[cell phone rings] Shoot, sorry. I just got a text. I'm so sorry.

Why don't you have a look in there and see the trains running? Oh, it's so much nicer in here than it is out there. When I first started out, I used to have to stand out in the sun.

-What? -Do you know when the next train's coming? -There's one coming right there.

-He has a great eye. [female voice] Attention, train approaching. [Michael] As with Elsa, every subject received a lesson in how to switch the tracks.

Why don't you go ahead and switch them? -Right here? -Yeah.

Go ahead. How does that feel? I was, like, exhilarated.

I was, like-- I got nervous. -[cell phone rings] -One second. Let me check this.

Hang on one sec. Ah. Someone has to be in here the whole time.

-I got it, yep, I'm here. -Okay. -Hello?

-[laughing] Breaker, one-nine, roger, copy that. He's actually tapping into the power of being in that position. [female voice] Attention, object on track.

[Michael] Here comes the test. Attention, object on track. Attention, train approaching.

[Greg] She's not moving. -Attention, train approaching. -Just watch his eyebrows.

[Michael] Oh, yeah. Eyes are going back and forth. Train approaching.

-Oh, she's worried. -Yeah. Train approaching.

I don't know what I would do in this kind of scenario. Train approaching. This is sort of that frozen pose that we see.

Paralysis in the face of danger is such a common reaction. Attention, object on track. Attention, train approaching.

Object on track. [Michael] Even with the train seconds away, some are still looking for others to take control. I'll go try and find him.

Okay. -[sings softly] -She's singing. This is self-soothing there, yeah.

[female voice] Object on track. Attention. -She's not moving.

-Oh, my gosh, wow. -Okay, -Is she gonna switch it? Train approaching.

Attention, object on track. Attention. End of test.

Everyone is safe. -What? -All right, let's go.

[Michael] Not one of these participants pulled the lever. Time to find out why. [Michael] Hello, J.

R. Oh, my gosh! How you guys doing?

-My name's Michael. -J. R.

Everything that just happened was an experiment. [laughs] This was an experiment. -Oh, my gosh.

-Okay. What were you feeling when you were watching that? Terrified!

I-- I just-- I was feeling a little anxious when I saw the train coming, like, "Oh, my God! " -Your heart is beating fast? -Yeah, a little bit, yeah.

Tell me what was going through your mind when you heard that first warning that a train was approaching? I thought about switching it, but then actually acting on it was a different thing. I kind of suspended my responsibility.

Like, I didn't know what to do, so I was just like, "Oh, I better not touch it you know, because I don't know if I'll screw something up. " I would assume that there would be-- out of those five guys, someone would've looked back. They were gonna get out of the way, of the train was already planning to stop.

I think they probably built those trains with some type of sensor or something like that. [Michael] "The train probably had sensors. " "The workers would've noticed.

" "I didn't want to touch the equipment. " These are all forms of attribution, when an individual assumes that others are either responsible for taking action or have already done so. -Both tracks had people on them.

-Right! And I just didn't know who should live and who should die. Do I switch it, do I not switch it?

I mean, either way, someone's gonna get really badly hurt. I didn't want that power. It was quite-- quite the test, I would say.

[Michael] It is quite the test. At this point, one subject had switched the tracks, and five others had not. But we weren't done yet.

Meet Cory. -Here, have a seat. -Much obliged, thank you.

This is cool. This whole module will interconnect with the entire nation if we wanted it to. But right now, we're looking at just track one on the left, track two through there.

-Nice. -These are many, many miles away. -Yeah, -But they're all live feeds.

Surveying the scene. Eagle's point of view. -[cell phone rings] -Yeah.

Let me see what this is. -Okay, I'll be right back. -Okay, got it.

[Greg] He's remaining engaged. [Michael] Here come the workers. Oh, no.

[female voice] Attention, object on track. Uh, yeah. So he realizes there's a potential problem.

I think he's gonna go out. Attention, train approaching. Um, there's a train coming?

Um. . .

[Greg] Okay. Attention, object on track. Uh, yeah.

Attention, train approaching. Okay, he realizes there's no one there, it's urgent. Okay, so this needs to go to.

. . Attention, object on track.

[Greg] Okay, he's rehearsing what to do. -Attention, train approaching. -Oh.

Track two. Do they not know? Attention, train approaching.

I know. They should see this. Object on track.

Attention, train approaching. -Attention, object on track. -[train horn blows] -Attention, object on track.

-Oh, my God. -End of test. -Okay, good.

Everyone is safe. -Hello? -Hi, Cory, my name's Michael.

There was just a-- almost an accident seemingly. -Cory, everything that just happened was an experiment. -Okay.

-No one was in danger. -For sure. These were just loops of video taken before.

This is a psychology experiment looking at how people behave. . .

-Okay. Okay, yeah. -.

. . in various circumstances.

So tell me how you were feeling. -Mainly a bunch of terror. -[Greg] Terror.

And responsibility, because I was at the helm. And just horrified about making a decision between, like, five people compared to one. It was very scary, to say the least.

-It was scary, right. -Yeah. Oh, yeah.

What was going through your mind as the train's coming down the track? It was mainly to warn them. There are-- just to reiterate-- What's coming up?

What's coming up right now? You don't want to have to choose between people. Right.

And that was really tough. Either like six families or one family? It was, like.

. . up to me, it felt like.

Yeah. It was interesting to me that you had such presence of mind. [Michael] Yeah, look for help and make a decision.

The one that everyone, if you ask them in a survey, says that they would like to be brave enough to make. Yes, so that was impressive, Cory, it really was. Thank you.

You know, I think it would be good to have you meet -some of the people who participated so you can see. -Awesome. Yeah, let's go do that, just follow us on out -and meet the actors.

-Awesome. [Michael] Cory showed us just how important the debrief was in this situation. Meeting the actors, which all of our subjects did, reinforced that this was not a reality.

So, Greg, trolley problem. -Mm-hmm. -I went into this thinking we're going to tease out some general truths about human nature.

However, what we've really seen is that you learn a lot about the individual. -Right. -Everyone had some explanation for their behavior.

-Yes. -Each one was different. Yes, each one person told themselves a story about what was happening according to the facts and their analysis of the surroundings and what was going on at the moment, but it's also based on their own background and experience.

Totally, there were people who were just frozen, realizing something was wrong and they weren't prepared. [Greg] J. R.

was a great example of that. He evaluated everything, but at some point just said, "You know, I don't know what to do. " Other people were ready to say, "You know what?

This isn't on me. It's on the technology. I'm sure it's being taken care of by others.

" Whereas someone like Cory, -someone like Elsa said. . .

-[switch clicks] -. . .

"No, I have to take control. " -[click] They still had some of those same thoughts, but I think what happened is they realized that if they did not do something, more people would be hurt. Neither of them really wanted to do something.

They both felt compelled to do something, 'cause they had to save lives. So was it worth doing the trolley experiment? I think it was definitely worth it.

Some of these participants, if not all of them, learned something about human behavior. Although it was a difficult experience, Elsa learned what inner strength she had, and I think we had saw that with Cory as well. Every single one of our participants felt like -they just contributed to something.

-Right. And they feel the value of what just happened. -Yeah.

-It's not just us. Wow. We've since followed up with our subjects, and all of them are doing well.

I'm glad we minimized risk by prescreening vulnerable individuals, debriefing the participants, and providing on-site counseling because doing so gave me confidence that we could explore this facet of human psychology ethically. We learned that there's a stark difference between what people think they would do and what they actually do when faced with a difficult moral dilemma. Instead of saving five lives, most of our participants did nothing, but is it wrong to freeze?

Should people feel bad for being unable to act? Well, here's the thing. Freezing in the face of a threat is a behavior that can be found all over the animal kingdom, but we are the only animals that can study how we act, pontificate on how we ought to act, and program machines to do only that.

To make progress in our study of the mind, we have to affect the mind, and that's not something that we should take lightly. Understanding who we are by taking ourselves to the limit comes with a risk, and as we've learned, that risk must always be balanced against the greater good. And as always, thanks for watching.

This season, on Mind Field. . .

You're going to be a lab rat in a maze. Nobody's ever done this before. It's quite pioneering work, really.

As far as I'm concerned, you're already a co-author on our scientific paper. - Ready? - Ready.

I'm here on the Amazon, where I will drink an ancients psychedelic drug-- ayahuasca. Don't worry, this is a self-driving car. We'll connect through Bluetooth to this living robot.

Okay, and then to the left. -Whoa. -Whoa-ho-ho!

I didn't realize that you were a real person. I'm gonna tear you apart if you don't give us some answers. I am going to be taking a lie-detection test.

-[buzz] -[crackling] You know, Chinese water torture isn't even Chinese. Will five people die, or will one? This is a big first for us.

We're actually getting to do this for real. Welcome to Mind Field. Thanks for watching!