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Hank: Studying the human mind is a tricky business. There’s still so much we don’t know, and so many questions scientists are looking to answer. But when researchers are working with human subjects, they have to balance getting answers with protecting their subjects.

In the past, they haven’t always been good about taking care of the fellow human beings they’re studying. A lot of historical psychology experiments would be considered unethical by today’s standards. And the foundation of the ethical standards we use today comes from the 1970s, when scientists came up with a list of rules to protect the security and privacy of human volunteers. It’s known as the Belmont Report: basically, three key ethical principles to guide all human research.

The first point is called respect for persons, and it means that subjects have to give informed consent. Anyone who participates in human research — including psychological research — needs to know the risks and benefits of the experiment before signing up. The second ethical principle is called beneficence, and it basically means that researchers should try not to have any negative impact on the well-being of the people who participate in their studies. Basically, “do no harm.” The final point, justice, involves making sure that subjects aren’t exploited. Researchers should also make sure that the burdens of the study and the benefits of the results are distributed fairly.

In early research studies, for example, the subjects would often be poor, while wealthier patients would benefit from the results of the experiment, and that’s not okay. These rules apply to human research in all fields, including psychology. But the code of conduct hasn’t always been so clearly defined.

And before it was, there were a lot of questionable studies being done. In the year 1920, a psychologist named John Watson wanted to show that humans can be classically conditioned — like what happened to Pavlov’s dogs. Basically, classical conditioning means pairing a stimulus, like food, that triggers a physical response, like drooling, with an unrelated stimulus, like a bell.

Even though a ringing bell, of course, wouldn’t normally make dogs drool, when Pavlov paired the sound with food, he conditioned the dogs to respond to the bell by drooling. Watson and his team decided to prove that this could be done in humans by classically conditioning a 9 month old baby named Albert using animals and scary noises.

First, the researchers presented Albert with a fuzzy white rat. As he’d reach out to pet the animal, the psychologists would strike a hammer against a metal bar behind his head, creating a loud noise to startle him. Eventually, just the sight of the white rat was enough to make Albert start crying and crawl away. He’d began to associate the fear of the loud, scary noise with the fuzzy white rat. So yeah, Albert had been conditioned.

But this study failed in a lot of ways. For one thing, it used a single subject and no controls. So Watson hadn’t really proved anything. But then of course there were the ethical issues. Watson never reconditioned Albert to not be afraid anymore, so he was permanently affected by the experiment, and not in a good way.

We also don’t know if Albert’s mother fully consented to the research. Which definitely violates the main ethical principles of the Belmont Report. And this wasn’t the only horrifying psychology experiment conducted on children in the early 20th century.

In the late 1930s, a psychologist named Wendell Johnson and his graduate student Mary Tudor at the University of Iowa wanted to know how positive and negative feedback affected the way children learned language. They decided to test this directly, by giving kids positive and negative feedback on speech disorders. That might not sound so bad, but there’s a reason why their experiment is now known as the Monster Study.

Tudor recruited 22 children from an orphanage, told them they’d be given speech therapy, and split them into two groups. Ten of these children — five in each group — had early signs of stutters. But, both groups also included kids with normal speech patterns.

The kids in one group were told they didn’t have a stutter. They were given positive feedback: that they’d outgrow the speech difficulties, and that they should ignore anyone who criticized the way they spoke. Meanwhile, those in the other group were told that they did have a stutter, and that they should never speak unless they could do it right.

As you can probably imagine, this didn’t go very well. The encouragement and criticism didn’t seem to have much of an effect on the children’s stutters. But the different kinds of feedback did have a huge impact on their self-esteem.

The kids with speech issues who got positive feedback didn’t lose their stutters, but they did become a lot more confident when they spoke. Meanwhile, the children who were given negative feedback became more withdrawn, self-conscious, and frustrated — whether or not they actually had a stutter to begin with. So for that group of kids, this research was pretty damaging.

As minors, they couldn’t consent to the research, and the people who ran the orphanage didn’t protect them from the potential harm of the study. The children also weren’t debriefed after the project was over, and there was no real follow up on how they may have been affected by the study long-term. All of these things were later declared unethical by the Belmont Report.

Experiments of course can harm adult subjects, too. In 1961, a researcher at Yale University named Stanley Milgram was interested in the psychology of obedience. He decided to see how subjects would react when a researcher pushed them to do things that went against their morals.

The study he came up with is now called the Milgram Experiment. And it had three separate roles: The Experimenter, played by a scientist in a white lab coat, was the authority figure. The Teacher was the role assigned to the experimental subject.

The final role was the Learner, a paid actor who the subject thought was actually another volunteer. The Learner was sent to a separate room so they were out of sight while the Experimenter observed the Teacher, the subject, instructing the Learner in a word-pairing task over an intercom. Every time the Learner got the word pair wrong, the Teacher pressed a button to shock them, with the voltage increasing by 15 volts for every wrong answer.

The subject believed they were shocking the Learner, but they were actually listening to an actor pretending to be in pain, complaining of chest pains, shouting, pounding on the wall, and eventually going silent. The experiment only ended when the Teacher had given the maximum 450 volt shock three times in a row, or when they refused to continue. 65% of the subjects did give out those maximum voltage shocks — just because a scientist in a white lab coat told them to.

Milgram concluded that people will obey authority figures even in morally questionable circumstances, and the experiment has since led to many more studies on the psychology of authority. But the subjects thought they were actually listening to someone being electrocuted on the other end of the line, even though they were told by the Experimenter that there would be, quote, “no permanent tissue damage.” Leaving your subjects feeling like they may have just killed someone doesn’t protect their well-being.

And they couldn’t have gotten informed consent, since warning participants about the experiment would have changed how they reacted. Since then, there have been other studies that led people to believe they might be hearing someone get seriously injured.

In 1964, a woman named Kitty Genovese was murdered. At the time, newspapers reported that there were more than 30 witnesses to the murder, and that none of them called the police. We now know that those reports were flawed, but for a while, it seemed like dozens of people just stood by while someone was murdered right in front of them. So in 1968, psychologists John Darley and Bibb Latané at Columbia University came up with a way to learn more about why people might not act in a crisis, especially if there are others around.

They placed college student volunteers alone in rooms, gave them headphones, and told them that the study was about the emotional issues faced by students. Each subject was told that they would be communicating with a few other students over intercom to avoid any privacy issues that might come up if they were face-to-face. But the other students on the line were actually recordings — and one of those recorded students mentioned early on in the conversation that they had occasional seizures.

Later on in the experiment, that voice would start to have trouble speaking and ask for help, saying that they were having a seizure. The researchers then measured how long it took the subjects to go look for help. They found that it took participants longer to respond when there were more people in the conversation.

The subject was less likely to do something if they believed there were other people who could intervene instead. It’s called the Bystander Effect. Understanding this response is important for investigating crimes and for protecting communities by teaching people to act during a crisis instead of assuming that someone else will do it.

But, like the Milgram Experiment, there are ethical concerns about how this research might have affected the subjects after the study was over. These days, it would be tough to convince a review board that the potential benefits of this kind of study outweigh the risks. Another study turned out to be so damaging that it had to be ended early.

In 1971, Philip Zimbardo, a psychology professor at Stanford University, wanted to learn more about how being placed in different social roles affected the way people behaved. He decided to simulate a prison and cast volunteer subjects into the roles of guards and prisoners. 24 white male college students were recruited into the study and separated into two groups: prisoners and prison guards.

Zimbardo acted as the prison superintendent. The prisoners were searched, then given ID numbers instead of names to dehumanize them. Meanwhile, prison guards were given uniforms and clubs and told to do whatever they had to do to maintain order, giving them power over the prisoners — and a sense of superiority.

The study was supposed to last for 2 weeks but was actually called off after just 6 days because the conditions in the prison went downhill so quickly. One prisoner had to be released from the study even earlier because the conditions in the jail made him panicked and disoriented. Other prisoners started a revolt because the guards had treated them so badly.

After that, the guards became more and more abusive, giving the prisoners physical punishments when they misbehaved, like forcing them to sleep on concrete and to strip naked. In the end, Zimbardo concluded that the subjects had internalized their assigned roles. The prisoners became submissive, while the guards became aggressive and abused their power over the prisoners. You could not do this study today.

By acting as the superintendent, it was impossible for Zimbardo to stay impartial. That’s a pretty big flaw in the study’s design — he was invested in the outcome of the research. Zimbardo also allowed the guards to subject the prisoners to serious abuse, and may have caused them real, permanent harm. So, again, that whole well-being thing was not really taken into consideration for this study.

Like the rest of the studies on this list, the Stanford Prison Experiment would not be considered ethical these days. But psychology’s sometimes-dark past has helped scientists realize that they have a responsibility to protect the public and the subjects of their research studies — which is why ethical standards are an important part of modern research. We want to understand the human mind, but in the process, we also have to protect the minds being studied. The standards laid out by the Belmont Report help us do just that.

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