Not everyone loves scary movies, but for the people who do, there are a few theories as to why—the main one coming down to hormones. When you're watching a scary movie or walking through a haunted house, you get all the adrenaline, endorphins, and dopamine from a fight-or-flight response, but no matter how scared you feel, your brain recognizes that you're not really in danger—so you get that natural high without the risk.

Why do you yawn when someone else does, even if you aren't tired? There are a few theories about why yawning is contagious, but one of the leading ones is that it shows empathy. People who are less likely to show empathy—such as toddlers who haven't learned it yet or young people with autism—are also less likely to yawn in reaction to someone else's.

In another University of Pennsylvania study, one group learned about a little girl who was starving to death, another learned about millions dying of hunger, and a third learned about both situations. People donated more than twice as much money when hearing about the little girl than when hearing the statistics—and even the group who'd heard her story in the context of the bigger tragedy donated less. Psychologists think that we're wired to help the person in front of us, but when the problem feels too big, we figure our little part isn't doing much.

When people are asked to recall items from a list, they're most likely to think of things from the very end, or from the very beginning, found one study published in Frontiers of Human Neuroscience. The middle gets muddled, which could also play into why you remember your boss wrapping up her presentation, but not so much about the middle.

Our brains have something called a "negativity bias" that makes us remember bad news more than good, which is why you quickly forget that your coworker complimented your presentation but keep dwelling on the fact that a kid at the bus stop insulted your shoes. To feel balanced, we need at least a five to one ration of good to bad in our lives.

Ever wonder why that sandwich from the takeout place down the street tastes better than the ones you make at home, even if you use the same ingredients? One study published in the journal Science found that when you make yourself a meal, you're around it so long that it feels less exciting by the time you actually dig in—and that, subsequently, decreases your enjoyment.

Researchers who published their work in the journal Nature have found that it's less stressful to know something negative is about to happen (e.g., there's no chance we'll get to a meeting on time) than when we don't know how things will work out (e.g., we might be on time after all). That's because the part of our brain that predicts consequences—whether good or bad—is most active when it doesn't know what to expect. If stepping on the gas will help us beat traffic, we'll go through that stress instead of just accepting that we'll have to come up with a decent excuse when (not if) we're late.

It's not just good manners—the "rule of reciprocity" suggests that we're programmed to want to help someone who's helped us. It probably developed because, to keep society working smoothly, people need to help each other out. Stores (and some frenemies) like to use this against you, offering freebies in hopes that you'll spend some cash.

Psychologists have studied a phenomenon called reactance: When people perceive certain freedoms being taken away, they not only break that rule, but they break even more than they otherwise would have in an effort to regain their freedom. This could be one of the best psychology facts to explain why a teenager who can't use his phone in class will chew gum while stealthily sending a text.

Don't blame your self-absorbed brother for talking about himself—it's just the way his brain is wired. The reward centers of our brains light up more when we're talking about ourselves than when we're talking about other people, according to a Harvard study.

"It's so cute, I just was to smoosh it until it pops!" That's called cuteness aggression, and people who feel it don't really want to crush that adorable puppy. Research published in Frontiers in Behavioral Neuroscience found that when we're feeling overwhelmed by positive emotions—like we do when looking at an impossibly cute baby animal—a little bit of aggression helps us balance out that high.

University of Glasgow researchers found that in the same way that we hear voices in our heads when we read aloud, our brains also "talk" over boring speeches. If someone is speaking monotonously, we'll subconsciously make it more vivid in our heads.

In one University of Michigan study, people with high testosterone remembered information better when it was paired with an angry face than a neutral one or no face, indicating they found the angry glare rewarding. The researchers said it could mean that certain people enjoy making someone else glare at them—as long the flash of anger doesn't last long enough to be a threat—which could be why that guy in the office won't let go of that stupid joke at your expense.

In a famous 1950s experiment, college students were asked to point out which of three lines was the same length as a fourth. When they heard others (who were in on the experiment) choose an answer that was clearly wrong, the participants followed their lead and gave that same wrong answer.

Research published in the Journal of Experimental Psychology shows that even when you think you're doing two things at once, what you're actually doing is switching quickly between the two tasks—you're still focusing on one at a time. No wonder it's so hard to listen to your partner while scrolling through Instagram.

Doesn't matter if you like where you're at right now or not—most of us have an "optimism bias" that convinces us the future will be better than the present, according to research in Current Biology. We assume we'll rise up in our careers, never get divorced, raise little angels of children, and live to a ripe old age. Those might not all be realistic for everyone, but there's no harm in dreaming.

Humans are victim to something called confirmation bias: the tendency to interpret facts in a way that confirms what we already believe. So no matter how many facts you throw at your uncle trying to sway his political opinions, there's a good chance he isn't going to budge. It's one of the psychology facts you'll just have to accept that you can't change.

Evolutionarily speaking, conserving energy is a good thing—when food was scarce, our ancestors still had to be ready for anything. Unfortunately for anyone watching their weight, that still holds true today. A small study published in Current Biology found that when walking on a treadmill, volunteers would automatically adjust their gait to burn fewer calories.

Researchers found that the fewer friends a person has, the higher levels of the blood-clotting protein fibrinogen. The effect was so strong that having 15 friends instead of 25 was just as bad as smoking.

The music we like gives us a hit of dopamine and other feel-good chemicals, and that's even stronger when we're young because our brains are developing. From around age 12 to 22, everything feels more important, so we tend to emphasize those years the most and hang on to those musical memories.

Even people with the best memories in the world can have "false memories." The brain generally remembers the gist of what happens, then fills in the rest—sometimes inaccurately—which explains why you insist your wife was with you at a party six years ago, even though she's adamant she wasn't.

When you see bright blue and red right next to each other, your brain thinks the red is closer than the blue, making you go practically cross-eyed. Same goes for other combinations, like red and green.

Your short-term memory can only hold on to so much information at a time (unless you try one of the simple ways to improve your memory), which is why you use "chunking" to remember long numbers. For instance, if you try to memorize this number: 90655372, you probably naturally thought something like 906-553-72.

Sorry, kids! One of the most useful psychology facts is that testing really does work. One study published in the journal Psychological Science found that people are more likely to store information in their long-term memory if they've been tested on the information (the more, the better) than if they just study and don't need to remember it right away.

The whole "paradox of choice" theory has been criticized by researchers who say it hasn't been shown in studies, but there is some evidence that our brains prefer a few options to a ton. When singles at speed-dating events met more people and those people had more diversity in factors like age and occupation, the participants chose fewer potential dates.

Psychologists have found that the brain is sensitive to scarcity—the feeling that you're missing something you need. When farmers have a good cash flow, for instance, they tend to be better planners than when they're tight for money, one study found. When you're feeling cash-strapped, you might need more reminders to pay bills or do chores because your mind is too busy to remember.

Researchers in one Science study fed volunteers false information, then a week later revealed that the facts weren't actually true. Even though the volunteers knew the truth (now), fMRI scans showed that they still believed the misinformation about half the time. It's one of the psychology facts to know that could make you smarter.

Most of us haven't seen Jesus in a piece of toast, but we've all noticed cartoonish faces seemingly staring back at us from inanimate objects. That's called pareidolia, and scientists think it comes from the fact that recognizing faces is so important to social life that our brains would rather find one where there isn't one than miss a real-life face.

Ever wonder why when one problem resolves, another one takes its place? It's not that the world is against you—but your brain might be, in a sense. Researchers asked volunteers to pick out threatening-looking people from computer-generated faces. "As we showed people fewer and fewer threatening faces over time, we found that they expanded their definition of 'threatening' to include a wider range of faces," writes researcher David Levari, PhD. "In other words, when they ran out of threatening faces to find, they started calling faces threatening that they used to call harmless."

Humans hate "cognitive dissonance": when a fact counters something we believe. That's why when, we hear that a loved one did something wrong or garbage, we undermine how bad it really was, or we tell ourselves that science exaggerates when a study tells us we really need to move more.

You may have heard of the Pygmalion effect before—basically, we do well when other people think we will, and we don't do well when people expect us to fail. The idea came from a famous 1960s study in which researchers told teachers that certain students (chosen at random) had high potential based on IQ tests. Those students did indeed go on to be high achievers, thanks to their teachers' expectations in them.

Told yourself you'd just quickly check your Facebook notifications, and 15 minutes later you're still scrolling? You're not alone. Part of that has to do with infinite scroll: When you can stay on the site without actually interacting and clicking, your brain doesn't get that "stop" cue.

Here's another great example of cognitive dissonance: Volunteers in one Psychology of Learning and Motivation study did a boring task, then were paid either $1 or $20 to convince someone that it was actually pretty interesting. The ones who were paid $20 knew why they'd lied (they got a decent reward) and still thought it was boring, but the ones who'd only gotten a buck actually convinced themselves it really was fun, because their brains didn't have a good reason to think they'd been lying.

You've probably heard about the famous Stanford prison experiment. (Refresher: College students were randomly assigned to be either a prisoner or guard in a fake prison, and the "guards" started harassing the "prisoners." It got so bad that the two-week experiment was canceled after six days.). That's pretty extreme, but later studies have found that when people feel like they're in a power position, they become worse at judging a person's feelings based on their facial expressions, indicating a loss of empathy.

Why, oh why, does cake have to taste better than vegetables? Well, because that's how we were primed for millions of years. For our ancestors, getting a quick hit of energy from sugar and then storing it as fat, or eating plenty of fat to keep our bodies and brains fueled meant more energy in the long run. But now that sugary, fatty foods are easy (a little too easy) to eat and overeat, our bodies are still primed to store that fat—even though we don't need it.

Pretty much everyone has procrastinated at one time or another, even though we know logically that it would make more sense to get a jump on our taxes than to turn on Netflix. We prefer urgent, unimportant tasks because we know we'll be able to complete them. There's also evidence that when we see the deadline looming in terms of days, rather than months or years, because we feel more connected to a day-by-day passing of time.

It's one of the oldest psychology facts in the books: In the 1960s, Yale psychologist Stanley Milgram infamously conducted an experiment that he thought would prove Americans wouldn't accept immoral orders like the Nazis had. For a "learning task," volunteers were told to deliver shocks to a "learner" (an actor, little known to the real volunteers) if they got an answer wrong. To Milgram's horror, the participants continued delivering shocks, even when the learner screamed in pain.

Research shows that in terms of income, people have a "satiation point" where happiness peaks and earning more won't actually make you happier. Different studies have suggested various amounts (one 2010 study said $75,000, but a 2018 survey said $105,000), but the point is the same: Constantly aiming for more, more, more won't necessarily do you any good.

Even if you haven't topped out to your happiest income, your money can still determine your happiness. You've probably already heard about research that shows we're more satisfied when we spend money on experiences (a nice meal out or theater tickets) than on possessions because it helps us socialize and feel more alive. But another study published in Science found another strategy for using money the most satisfying way: spending on other people instead of ourselves.

“Once you start making the effort to ‘wake yourself up’—that is, be more mindful in your activities—you suddenly start appreciating life a lot more.”

–Robert Biswas-Diener

“We are what we are because we have been what we have been, and what is needed for solving the problems of human life and motives is not moral estimates but more knowledge.”

–Sigmund Freud

“Probably the biggest insight… is that happiness is not just a place, but also a process. Happiness is an ongoing process of fresh challenges, and it takes the right attitudes and activities to continue to be happy.”

–Ed Diener

“The world makes much less sense than you think. The coherence comes mostly from the way your mind works.”

–Daniel Kahneman