Previous: Slavery, Ghosts, and Beloved: Crash Course Literature 214
Next: Langston Hughes and the Harlem Renaissance: Crash Course Literature 215



View count:2,723,001
Last sync:2023-05-13 07:00
Feeling motivated? Even if you are, do you know why? The story of Aaron Ralston can tell us a lot about motivation. In this episode of Crash Course Psychology, Hank tells us Ralston's story, as well as 4 theories of motivation and some evolutionary perspectives on motivation.

Want more videos about psychology? Check out our sister channel SciShow Psych at!

Introduction: Motivation 00:00
What is Motivation? 1:08
Evolutionary Perspective: Instincts 1:29
Drive-Reduction Theory: Homeostasis & Incentives 2:37
Optimal Arousal 3:39
Maslow's Hierarchy of Needs 4:49
How Sex Motivates Us 5:29
How Hunger Motivates Us 6:32
Effects of Hunger & Starvation 7:59
How Social Belonging Motivates Us 9:33
Review & Credits 10:34
Crash Course is on Patreon! You can support us directly by signing up at

Want to find Crash Course elsewhere on the internet?
Facebook -
Twitter -
Instagram -

CC Kids:

You've probably heard this story: Aron Ralston was out climbing in Utah's Blue John Canyon when a giant rock shifted under his feet and he fell, pinning his right arm to the canyon wall. He was stuck, and worse, he hadn't told anyone where he was going. For the next five days, Ralston tried to move the rock; he ate his remaining food, drank the last of his water, eventually he drank his own urine, and started videotaping his goodbyes. But then something happened: Ralston had a dream. He saw himself as a father picking up his son, and with that vision an overpowering will to survive kicked in. He broke his arm bones, sawed through his flesh with a dull pocketknife and freed himself. Ralston harnessed some of our most powerful psychological forces: hunger, thirst, desire to be part of a family, need to return to the human community. They ignited his tenacity, which allowed him to do an incredible thing. They harnessed the power of motivation. Obviously in a big big way.

 Opening credits

In its most basic sense, motivation is the need or desire to do something, whether that need is biological, social or emotional, and whether that something is making dinner, going to college or cutting off your arm. Motivation is what gets you moving.

The big question is why? Why do we do anything? I mean why ever bother changing out of my sweat pants?

Psychologists often view motivation in one or more of four ways. On their own none of these theories is perfect but taken together they help us understand what drives us.

Let's start with the first theory, an evolutionary perspective. For a while, in the early twentieth century it was popular to think of all behaviors as instincts or innate drives to act a certain way, but this so called instinct theory was misguided in part because the presence of a tendency doesn't always mean its supposed to be there.

Like we can imagine why a bunch of people might start rioting at a heated soccer match,  but to say that they are supposed to, a little short sighted. Evolution is a far more complex, chaotic, and interesting process than that. Plenty of behaviors could just be accidents of evolution. Late paleontologist Stephen Jay Gould called these accidents "spandrels", or traits that rather than being adaptive just stuck around as byproducts of other processes.

Today we define instincts as complex, unlearned behaviors that have a fixed pattern throughout a species. For example, dogs instinctively shake their fur when wet, salmon return to the stream in which they hatched and human babies know how to suckle just minutes after being born. These are true genetically predisposed instincts that do not require learning, but today we understand that while certain tendencies may be genetic individual experience plays a major role in motivation as well.

So an other theory of motivation suggests that a psychological need, or drive, simply compels us to reduce that need. This is called the drive reduction theory. This could be as simple as hearing my stomach growl and looking for a burrito. My need is food. My drive is hunger. My drive reduction behavior is burrito. Drive reduction is all about maintaining your body's homeostasis, the balance of its physiological systems. As much as we're pushed to reduce our drives, we're also pulled along by incentives, the positive or negative stimuli that either entice or repel us. The mouth watering smell of that burrito pulls me toward it just as much as my hunger pushes me there. However, we're also clearly more complicated then our homeostatic systems and drive reduction theory may over simplify a lot of our behavior. For example, a person may fast for day ignoring their body's hunger to honor some spiritual or political cause, and I know I'm not the only one who sometimes eats when I'm not actually hungry.

So a third theory. The theory of optimal arousal attempts to fill in some of those gaps. It suggests rather than just reducing a drive  or tension like hunger we're motivated to maintain a balance between stimulation and relaxation.

Say you're hold up in your house all weekend studying. You're board and lonely and getting weird, so you call up some friends to go mountain biking, or to go to a karaoke bar or whatever you like to do for stimulation. The idea here is that you want to hit the right level of arousal, which take note psychologists often use in a nonsexual sense, without getting over stimulated or stressed. So if you nearly break your face on that bike ride or the Journey covers at karaoke start getting to intense you may need to back off. Take a nap.

Of course, everyone has a different level of optimal arousal, and I'm guessing Aron Ralston's was fairly high. Adrenaline junkies may jump out of planes to hit their ideal level, whereas others may be satiated by an engaging book or a knitting pattern. No matter which, the optimal arousal theory suggests that we're motivated to avoid both boredom and stress. And obviously, not all needs are created equally. If I'm suffocating and can't catch a breath, I'm not going to be thinking about eating that burrito, and if I'm about to be ravaged by lions, I'm not going to be worrying about my next paycheck.

American psychologist Abraham Maslow illustrated this shuffling of priorities in the mid-1900s with his famous "hierarchy of needs". At the bottom of the pyramid, you'll find our most basic physiological needs for food, water, air, and moderate temperatures. The next rung up speaks to our need for safety, then comes love and belonging, followed by esteem or respect, and finally - once all those needs have been met -  we have the relative luxury of being motivated by self-actualization and spiritual growth and yoga retreats and stuff. Of course, there are problems with Maslow's vision. Empirical research hasn't really supported his hierarchy, we tend to skip around on that pyramid all the time, and the importance of those higher-level needs may vary depending on our culture and finances and personality. But still, everyone is restricted by the lowest levels of the pyramid, and so regardless of theories about why we have them, most schools of psychological thought agree that we are driven by at least three big motivators: sex, hunger, and the need to belong.

We'll do a whole lesson later on all sorts of sex-related stuff, including how it motivates us... there's a lot there. 

For now, let's just say that sexual motivation is how we promote the survival of our species through recreation and/or procreation, both of which help human communities bond and expand. Without it, none of us would be here today thinking about burritos and severed arms and sex and stuff. Internally, we are biologically driven to knock boots by our sex hormones.  We are also motivated by psychological and socio-cultural influences ranging from suggestive external stimuli plastered all over billboards, magazines, and TVs in the form of, you know, like scantily clad bodies sprawled out on beaches, to more genteel desires like love and family or adherence to personal religious and cultural values.

Sex is a big motivator, but it isn't precisely a need. No matter what anyone has told you, people don't die without it. Hunger, though. After air and water, food is our body's greatest need. And thus, obtaining food is one of our greatest motivations. Hunger may seem pretty simple: eat food, stay alive; but physiologically and psychologically, there is a lot going on, and like so many things, it starts in the brain.

The sensation of hunger usually begins with a drop in your blood sugar level. Glucose is our body's primary source of energy, and while you may not initially feel a drop, your brain will. Your hypothalamus monitors your blood chemistry and responds to both high levels of the hunger hormone ghrelin and low levels of glucose by triggering that feeling of hunger, reminding you to eat something. I am in fact experiencing it right now.

Once you've eaten that burrito, your metabolism takes over, converting that food into energy, but while our physiological need for calories varies depending on our body size and composition, your gender, and your age, our hunger is also shaped by our psychology, culture, and mood. And these factors don't just rule when we're hungry, they also guide what we're hungry for. Biologically speaking, most humans and many other animals have a genetic taste for sweets and fatty foods because they're typically high in energy, but other taste preferences are conditioned through experience and culture. I may have an aversion to oysters because they once made me sick, and love gingerbread cookies because my grandma used to make them. Although popular in Cambodia, I'm not too keen on eating fried tarantulas, just like lots of folks around the world think the very idea of peanut butter is gross. Still, the feeling of hunger affects us the same. 

During World War II in the U.S., some conscientious objectors volunteered for medical research as an alternative way to serve their country. Perhaps the most famous of these studies was physiologist Ancel Keys' Minnesota Hunger Experiment, which measured the effects of semi-starvation by partially starving its volunteers. While ethically dubious, the experiment was geared toward understanding the many small and large effects of hunger which was plaguing Europe at the time. The study started in 1944 by feeding 36 young, healthy men a normal diet for three months, then a halving their caloric intake for six months, then slowly rehabilitating them to normal weight during the last three months. They ate mostly wartime foods like root vegetables, bread, and pastas, and were required to walk 22 miles and participate in various work and educational activities for forty hours each week. The goal was to see a 25% drop in body weight during the starvation period. And, as you can imagine, the changes were dramatic. The men became gaunt and listless and showed a decrease in strength, heart rate, and body temperature, but the psychological effects were perhaps even more dramatic. The men became totally obsessed with food; they dreamed about it, talked about it all the time, read cook books. They lost interest in sex and jokes and social activities. They were irritable, anxious, and depressed. In the end, they were all rehabilitated, but the study gave us some understanding of the devastating psychological effects of starvation. It also showed us something of the social effects. As men withdrew from one another and isolated themselves, as one fundamental need was frustrated, these men experienced the decline of another: the need to belong.

Humans are social animals. Evolutionarily speaking, it's fair to say that social bonding has helped us survive. It's a tough world out there and we've got a lot better shot at thriving if we're sharing resources and responsibilities, protecting and supporting each other in groups. That isn't to say you need to be joined at the hip with everyone. Our social needs have to be balanced with out autonomy, our sense of personal control, so we feel both connected and independent.

But sometimes we're denied that sense of belonging. We've all experienced the pain of being ignored or rejected at some point in our lives. It's worse than just about anything. The evidence for this is abundant. One recent study suggested that teenagers who had a sense of belonging to their community had better health and emotional outcomes than those who didn't feel like they belonged. Cultures all over the world use ostracism or social exclusion as a type of punishment, whether it's kids in time-out, adults in exile, or prisoners in solitary confinement, separation feels like a punch in the gut. 

Never underestimate the power behind what motivates us. The need to survive, the need to belong, if you can harness that motivation, you can do just about anything. Just ask Aron Ralston.

If you were motivated to learn today, hopefully you took in four theories of motivation, including the evolutionary perspective, drive reduction, optimal arousal, and Maslow's hierarchy of needs, and how sex, hunger, and the need to belong motivate us.

Thanks for watching, especially to our Subbable subscribers who make this whole channel possible. If you'd like to sponsor an episode of crash course or even be animated into an upcoming episode, just go to

This episode was written by Kathleen Yale, edited by Blake de Pastino, and our consultant is Dr. Ranjit Bhagwat. Our director and editor is Nicolas Jenkins, the script supervisor is Michael Aranda, who is also our sound designer, and the graphics team is Thought Cafe.