 This is lecture 12. In this lecture we're going to turn to the dark side of human behavior. We're going to talk about our tendency to harm others. And in this part of the lecture we'll discuss why do we have this tendency. There's of course several theories that can help us explain aggressive behavior. But let's start by giving a definition of aggression. I think we all can have a gut feeling of what aggression is and what it looks like for example like this. But it's important to really understand the meaning of aggression. So aggression is, first of all, behavior. It's not having nasty thoughts or mean thoughts about someone or the idea of wanting to harm someone. No, it's actual behavior towards another person. And this behavior is harmful. And it can either entail physical harm or psychological harm. Both forms are also captured under the bigger umbrella term of aggression. So aggression is also important to know that it's different from assertiveness, from standing up for yourself. Because when you're standing up for yourself, your goal is to protect yourself. But with aggression, your goal is to hurt someone. It's always directed at someone else. So there's a lot of variations in aggressive behavior. And we have this maybe if you think about aggression, you think about someone punching someone else. And that is indeed aggression. That's a form of physical aggression. But also, for example, calling someone names, shouting at someone in an aggressive manner and saying very mean things to a person, that's also aggression. That's verbal aggression. So you have physical versus verbal aggression. But you also have direct versus indirect aggression. And direct aggression is aggression that is just face to face immediately towards that person. While indirect aggression is behind someone's back. For example, gossiping is also a form of aggression with the intention to harm a person. And you're not doing that towards the person directly confronting this person, but behind someone's back. So that's an indirect form of aggression. Then the next variation is between offensive and defensive aggression. And so I think you can have an idea of what that means. Offensive means that you're really attacking a person and defensive means that you're protecting yourself. You're responding towards aggression of another person. And then finally, there's a difference between hostile and instrumental aggression. And I'll explain that in the following with the following example. So hostile aggression is aggression that is very impulsive. If you behave in a hostile, aggressive way, you're probably provoked. You're probably being made very, very angry. And you're just acting out immediately, aggressing to someone else. And your only goal with hostile aggression is hurting that person. So you're just, you're very emotional. You're enraged. And you're just, you know, you're not thinking about the long-term consequences. You're just acting out because you're so frustrated, so emotional, and you're showing aggression. This is in contrast to instrumental aggression, which is also a form of aggression, but then aggression itself is actually a means to an end. So think, for example, about someone robbing a bank, using aggression. But then in that sense, the goal of the person robbing the bank is not to behave aggressively. No, it's to steal money. So if you use instrumental aggression, you're using aggression as a means to an end, as a means to achieve a different goal, a goal that is not related to harming others. So that can also be self-defense, for example. If you are, for example, you see someone attacking a kid and you're interfering or punching someone to protect the kid, then you're actually showing instrumental aggression in which you're hurting one person, but with the bigger goal of protecting someone else. So it's important to know the difference between these two types of aggression. So aggression is really very complicated behavior, and it can take many, many forms. Of course, a key question, also the key question of this part of the lecture is, why do we behave aggressively? And as always, psychologists do not necessarily agree with each other on this. There are several theories. Basically, four different theories that we're going to describe. First of all, the idea that aggression is essential for survival. So it's just one of these tools that we can use as human beings in order to survive and also to reproduce. Aggression is a biochemical reaction. That's also one perspective on aggression. It's learned social behavior, or it's a response to being frustrated. So we'll zoom into all these different explanations one by one. Starting off with the first explanation, aggression is essential for survival. So I guess I hope that at this point in the course, you can predict which bigger theory will embrace this explanation. It's evolutionary theory. And according to evolutionary theory, basically everything we do has this bigger goal of protecting ourselves, making sure that our genes live on or reproducing. So in lecture 11, when we talked about helping behavior, we talked about the concept of kin selection. And that means that we're especially likely and eager to help others that are related to us, genetically related to us, especially our children, especially our own little family, but also the bigger family. We want to protect them in order to make sure that our genes survive and live on. When kin selection can actually also predict aggressive behavior. Because if someone hurts or wants to hurt someone in your direct family, then evolutionary, it makes a lot of sense to behave aggressively, use instrumental aggression in order to protect your family. Also, according to evolutionary psychology, kin selection can explain why there are differences between males and females in aggression. Because according to evolutionary theory and this idea of kin selection, males are more physically aggressive than females. First of all, because they want to have dominance, established dominance over other males. So they want to be like the top male and also to ensure their paternity. So that can help explain why males are more aggressive when a female is sexually unfaithful to them than females are. So that's the idea of evolutionary theory. We want to protect our family. We also want to make sure that our genes actually live on so that we are able to reproduce. So this is also in line with this more general idea and stereotype that males are more aggressive than females. So the idea that men are more aggressive. And this is actually in contrast to helping behavior, what we discussed in lecture 11, where this idea is that women are more helpful and men are more aggressive. So to what extent is this actually the case? Men are actually more aggressive than women if you look at the numbers. Well, if you look at very extreme forms of aggression, the picture is crystal clear. So let's take the most extreme form of aggression I can think of, murder, committing murder. So who commits murders? Is it males or females? So let's look at the numbers here. So here you see the percentage of cases in which a murder is committed by a male, that's the upper line, male offender and a male victim. That's in 65% of the cases. So in the majority of the cases, both the murderer as well as the victim is male. Then the next biggest category is male offenders and female victims. So a man killing a woman. That's in 22% of the cases. Then if we look at female offenders, so female murderers, that's really a minority. It's only 12% of the cases that females commit murders. So that's pretty overwhelming results here. So you see that when it comes to committing murders, men are way more likely to be aggressive. Also, if you look at other forms of extreme aggression, like rape or really harmful, extreme forms of harmful physical attacks, then males are definitely more aggressive than females. If you look at more subtle forms of aggression, less physically harmful, the picture is definitely different. So there's actually some evidence that women use more indirect aggression than men. So gossiping, for example, that's something that women are more likely to do. And when it comes to verbal aggression, they are both more or less equal. But it's definitely safe to say that males, when they do aggress, the responses or the consequences are much more serious often. So why is this the case? Why should males be more aggressive? So okay, we have this evolutionary theory about it, but it might also have something to do with this substance, testosterone, probably something you're familiar with or you've heard of it. Testosterone is a hormone that both men and women have, but generally males have higher levels of testosterone than females. And this seems to have something to do with aggression as well, if you look at the evidence. For example, if animals in a laboratory are injected with testosterone, they become more aggressive. So injecting animals with testosterone increases their level of aggression. And then if you look at human beings, and then we look at, for example, archival data or correlational studies, then we see that if you study the naturally occurring levels of testosterone, for example, prisoners that are convicted of violent crimes versus prisoners that are convicted of nonviolent crimes, there's a difference as well. So people that are in jail basically because they have been violent also have higher levels, baseline levels of testosterone. Also, if you compare the level of testosterone of juvenile delinquents with college students, there's a difference there as well. Of course, with all these studies, it's important to keep in mind that overall, these are correlational studies. And you of course know that if you have a correlational study showing a relationship between factors, you cannot make any causal implications. So you cannot say testosterone leads to more aggression. And actually, it's also been shown to be the other way around as well, in the sense that the moment you start showing aggressive behavior, your testosterone levels rise. So there's this cycle here that is going on. And then also, if we zoom into testosterone, picture seems to be a little bit different. So in general, testosterone is mostly related to instrumental forms of aggression. So not this hostile direct forms of aggression, but more levels of aggression that you use as a means to an end in order to achieve a bigger goal. This is, for example, stated in the challenge hypothesis that states that testosterone only relates to aggression when there are opportunities for reproduction. So if the moment you feel especially males have this opportunity to reproduce, then their testosterone levels can predict the aggression that they demonstrate. And according to the dual hormone hypothesis, testosterone only relates to dominant behavior when cortisol, which is stress hormone, is low. So only if you feel confident, if you're relaxed, then higher levels of testosterone will show, will relate to more dominant behavior. So yeah, so the picture of testosterone is a bit complicated, but definitely it has something to do with showing aggressive behavior. And testosterone is actually the first example of biochemical influences, which is the second explanation for aggressive behavior. So maybe people aggress just because they are bio biochemically induced to do so. So with higher levels of testosterone, for example. But another example of biochemical influences is alcohol. Alcohol does not necessarily lead to higher levels of aggression in itself. But what alcohol does is it lowers your inhibition. So you become more impulsive. And in being impulsive, especially in, for example, a bar area might be related to more aggression, you lose the abilities to sort of calm down, count to 10, and not instantly respond to being provoked, for example. And especially the combination testosterone and alcohol, yeah, that can lead to nasty consequences, as is also evident in the high numbers of males showing aggressive behaviors when they are going out way higher than females. So if you look at biochemical influences, an interesting question that you can ask yourself, is there also substance that lowers aggression that makes people, you know, more relaxed, less likely to aggress? And that is actually the case. So serotonin, which is sort of the happy hormone. If you are higher in serotonin, you're less likely to aggress. So serotonin is good. We all need to be very happy. You can also induce or influence serotonin levels and how you can do that. I think maybe some of you already know this. That's by using a certain type of drug, especially MDMA. So if you use MDMA or ecstasy, which MDMA is the substance in ecstasy that has its effects on your hormones, then serotonin levels go up and you become less aggressive. So if everybody goes out and only takes ecstasy or MDMA, it's very happy scenery. No barfights in that club. So before we get too excited about MDMA and using it, or if you have the idea that I sort of influence you to use this substance, I just want to make sure that I put places into perspective and explain a little bit about the relationship between serotonin and MDMA. So if you use MDMA, then serotonin in your the effects, serotonin goes up. So you see more serotonin in your blood and you see that in this little picture, you see on normal circumstances the amount of serotonin in the blood and then during ecstasy, there's way more serotonin. So that leads to this very happy feeling, low levels of aggression. You feel very, very good. But then after ecstasy, you actually have less serotonin in your blood and you can get feelings of depression, feelings of anxiety and sort of the normal amounts of serotonin are basically used up by your brain through the use of MDMA and ecstasy. And this is something that we know and you might be thinking to yourself, so okay, so after you use MDMA, then temporarily you just become a little bit depressed. Well, that's fine. I can live with that. But there's actually evidence that using MDMA also have long term effects on your brain structures and it can actually change the brain's capacity to produce serotonin. And this is shown in a research done on monkeys. And these monkeys was actually a very sad study. It was a study in which monkeys first phase was very happy because these monkeys were given ecstasy. They were given ecstasy for four days in a row, two times a day. So quite, you know, heavy partying for these monkeys for four days, high use of ecstasy MDMA. And then after two weeks, half of these animals, half the monkeys were killed and their brains were studied and the brains were studied for how much to study basically how much serotonin they would still have in their brain structure. And this is what you see here. So in the control condition, you see the amount of serotonin present in the brain. And then after two weeks after ecstasy, there's barely any serotonin left. So even two weeks after this heavy partying of the monkeys, they barely had any serotonin. So they felt really depressed. And some of these monkeys still lived on and they lived on for seven years. And after seven years still, the researchers killed them, looked at their brains, and they saw that even seven years after ecstasy, use of ecstasy, this very intense use of ecstasy, these serotonin levels did not come back to normal. So this study indicates, and it's with monkeys, not with humans, luckily, of course, still very sad for the monkeys. But you see that there's some evidence, and this is not the only study, but there's more, let's show that just using MDMA can really mess up your brain's reproduction of serotonin. So please be careful with that, if you are interested in that substance. Okay, so now let's quickly move on to the third explanation for why people are aggressive. And this is an explanation that is under the bigger theory of social learning. And we already talked about this quite elaborately. So social learning is the overall idea that we learn by imitating others, especially our caregivers, caregivers, our parents, if they show certain behavior, we are very likely to copy it. We are copying animals. So we look at other behaviors and we show this as well. So if your parents are very aggressive, then you're also more likely to behave aggressive as well. Especially if your parents give you examples of when to show aggression, for example, when being frustrated or maybe aggression if you're driving a car or if you're in a certain area when you're provoked. Then you learn this response of being aggressive as a child from a very young age on. So you can actually see the impact that social learning and the social cognitive learning theory has on the behavior of kids in a very nice little video. This video is a video of the Bobo doll experiment, which is conducted at Stanford University in 1961. So quite some time ago. And you will see how children respond to a situation in which they first demonstrate how an adult interacts with a Bobo doll, which is a plastic inflatable doll. And you then see how the children will behave in a similar situation. So take a look. The Bobo doll experiment was a study conducted by Albert Bandura to investigate if social behaviors can be learned by just watching others in the action. In the hit television show, Big Little Lies, tensions run high as an unknown child is accused of choking another student. And throughout the series, this is a little spoiler, the child is revealed as the character Max actually has an abusive father. And once Max's mother realizes that her child is learning behaviors from her husband, she decides to take action. And this cycle of abuse is very sad, but it's extremely common in today's world. Many abusers were abused themselves or grew up in an abusive household. These ideas might seem obvious, but in the mid 20th century, evidence that support these ideas were just starting to become known. So what is the Bobo doll experiment? In 1961, Canadian American psychologist Albert Bandura conducted this experiment at Stanford University. He placed a few children in a room with an adult, some toys, and a five foot tall Bobo doll. If you don't know what that is, a Bobo doll are large inflatable clowns that are kind of shaped like a bowling ball pin. So they always roll upward if they're punched or knocked down. Anyways, this experiment made Albert Bandura one of the most famous psychologists in the history of the world. To this day, he is listed in the ranks of Freud and BF Skinner. And in this video, I'm going to explain the Bobo doll experiments, how they change the world of psychology and how they still have an impact on us today. So let's get started by talking about Bandura's first Bobo doll experiment. It was in 1961. And he conducted this experiment in three different parts, modeling, aggression arousal, and a test for delayed imitation. So stage one was modeling, and the study was separated into three groups, including a control group. Two of the groups were in a room with a model who was basically just an adult. One group witnessed the adult punching the Bobo doll repeatedly, using harsh and aggressive language against the inflatable clown. And some of these models chose to hit the Bobo doll over the head with a mallet. Now the second group actually did not see this behavior. They simply observed the model playing with blocks or coloring or doing other non aggressive childhood activities. The idea here is to separate the groups to see if they are actually watching the models, and then if they imitate those behaviors. So stage two is aggression arousal. So after 10 minutes of being in the room with the model, the child was then taken into another room. Now this room had all kinds of attractive toys. And briefly the researchers let the children play with these toys. But once they were engaged in the middle of playing with them, the researchers came in and took the toys away. And then they brought the children into another room. Now it's easy to guess, and that was actually the point that the children were frustrated. But the researchers wanted to see what these children would do and how they would release their frustration. This stage is called aggression arousal. Now stage three is actually the test for delayed imitation. So the third room contained a set of aggressive and non aggressive toys. The room also had the Bobo doll. Researchers watched and recorded each child's behavior through a one way mirror. You might be asking, what happened? Well, as you can probably guess, the children that observed the adults hitting the Bobo doll were actually more likely to take out their frustration by hitting the Bobo doll. They kicked, yelled at, and even used the mallet to hit the doll on the head. I think one of the most important parts is that the children that observed the non aggressive adults were more likely to stay away from the Bobo doll and take their frustration out without aggression or violence. And this means a lot. It means from an early age, sometimes, and mostly too early to remember, we are actually learning how to cope with frustration and negative situations just by watching our parents. And the problem is nobody picks their parents, which means you could be modeling healthy behavior or really unhealthy behavior. So then we're moving on to the final explanation of aggressive behavior. And that is the frustration aggression theory, which is a very simple theory basically stating that the moment that people get frustrated, they are more likely to become aggressive. Pretty simple, huh? We don't even need a theory for that. So just some zooming in, what is frustration or what is being frustrated, what do they mean with that? That's basically if you get hindered in reaching your goal. So if you want to reach a certain goal, and you're hindered in that, then we can become very frustrated like this man over here with his non working computer, very relatable to me. And we become even more aggressive when the goal is or was very close to us. So when we were nearly there, and if the frustration is unexpected, then we also become even more likely to behave aggressively. The frustration aggression theory can also explain why there's more aggression in certain parts of the world. For example, a part of the world in which there's huge variation between high and low incomes like you, like as witnessed here in this picture. So if this is the case, this is a situation of relative deprivation. And relative deprivation means that people experience a discrepancy difference between what they have and what they think they should have, especially when they compare this themselves to similar others. So all the people that live in this part of the town of the city, in which there's very low resources, they are very poor, they don't have anything, and then they're continuously showing examples of their neighbors that have it all. And what is the difference between them? They're the same age, they live in the same country, but then still there's this huge variation. This is very frustrating if it feels super unfair that some people have something and you don't have it for very random reasons, basically just why you that you were born on the other side of the world basically. So in these areas of the world in which there's a lot of relative deprivation, a lot of income inequality, we definitely see more criminality, more aggressive behavior, more conflict also in schools, in children. Children are also more aggressive in these areas, and this this is very likely due to this relative deprivation and frustration that people experience. But now we've come to the end of this part of the lecture, it's important to know that all these theories can help us understand that we sometimes behave aggressively, but sometimes we also do not behave aggressively. So the situation definitely plays a major role in our likelihood to aggress, and in part two of this lecture we're gonna dive more into the role of the situation when it comes to aggression.