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We've all been there — stuck in a long class or meeting, promising yourself you will. NOT yell at the next person who opens their mouth, and if you can just get through this, you can eat.

Visions of sandwiches and pizza dance in your head, because you're hangry. And being a little peckish doesn't just make us ornery. It also has significant effects on our behavior, especially on our impulsiveness when it comes to decision-making.

And those effects tend to be a lot more powerful than we realize. The research we're talking about today was carried out mostly in individuals who were fasting temporarily. We're not going to be talking much about food insecurity, which is a serious problem that comes with its own suite of psychological effects.

Rather, this is the psychology of what happens when your lunch is an hour late. You've probably heard that it's best not to go to the grocery store on an empty stomach. Studies show that hungry shoppers are more likely to buy more food that's higher in calories and lower in nutrients.

But that barely scratches the surface, because hunger affects all your decision-making abilities — not just decisions about food. And you might think that's no biggie; just focus a little harder until you have time for a snack. But here's the kicker: you can't always tell that your hunger is messing with your decision-making, making it harder to just reason yourself out of it.

For instance, a 2016 study found that fasting participants were more impulsive in performing computer-based tasks. But in questionnaires, those same people didn't rate themselves as being more impulsive when they were hungry — even though the data showed they were. A lot of what's happening in our brain and body when we're hungry stems from our evolutionary past.

We really, really need food to survive, so the drive to seek it is pretty powerful. So when you're hungry, you're programmed to prioritize getting some food in your face over, like, controlling your impulse to snap at Steve for interrupting your presentation. We're filming here.

Some of that has to do with a concept called projection bias, which is our tendency to think that we'll feel the same way in the future as we do now. A 2016 study looked at a pool of 89 people and their willingness to pay for delicious sheep's milk cheese. The researchers asked participants to make bids on the cheese, which they were told would be delivered to the highest bidder from each group the next day.

Subjects who were hungry during the auction were willing to fork over more cash for the cheese, even though they weren't going to receive it until the next day. The study also looked at projected hunger. Participants bidding on cheese to be delivered before lunch the next day — when they expected to be hungry again — also bid higher for that tasty treat than people bidding on cheese they'd receive after lunch.

When it comes to our evolutionary history, outside of air and water, food is pretty much at the top of people's needs. So when you're hungry, decision-making about, well, anything else drops a notch on your priority list, and you might be less inclined to keep the big picture in mind. One 2019 study suggested that hunger makes people more likely to choose smaller rewards now than larger rewards later, even if the reward didn't have much to do with food — like money and even music downloads.

Another study from 2010 compared college students who drank full-sugar soda with those who had diet. Those who drank the real sugar stuff had higher blood glucose levels and were more likely to choose a bigger cash reward in a month than a smaller one the following day. But hunger doesn't just impact either-or kinds of decisions.

Like, studies of blood glucose in participants who'd eaten breakfast versus those who hadn't suggest that hunger also takes a toll on your memory. For example, one experiment in the 90s involving 184 subjects found that those who had higher blood glucose levels, were better able to recall words from a list they'd studied earlier. All of this doesn't bode well for decision-making while your stomach is yelling at your brain to hurry up and feed it already.

Experiments suggest that hunger affects risk-taking behavior, influences the rulings judges hand out, and even makes us more likely to express prejudices or stereotypes we already hold. And listen, we wish we could tell you that you can just harness your inner gumption and not let skipping a meal mess up... whatever decisions stand between you and living your very best life. But the science says that it's not that easy.

Some of that probably has to do with mood. We know that hunger makes you somewhat grumpier than you would be in a satiated state, and you can't just snap out of it. And even though scientists are still teasing out how being hungry makes people more impulsive, it seems like hunger takes over a bunch of cognitive processes and can transform you into a hangry monster until you eat.

On a neurological level, finally getting a bite to eat affects the circulating levels of hormones like ghrelin. Once you've had a snack, levels of ghrelin go down, and so does your interest in taking risks — unless that snack and ghrelin drop are too small, which can cause risk-seeking to go up. So yeah — if you're hungry and you're about to make a big decision, know that you may well feel differently about things after a meal.

The good news is, research into how hunger affects our decisions has the potential to really help people — and not just people stuck in meetings after the donuts are gone. Like, some experts say that understanding how blood glucose levels affect people's short-term decision making could reveal new ways to treat compulsive and impulsive disorders, eating disorders, and addiction. Researchers are also still looking into the difference between cognitive effects of short-term hunger, like a skipped meal, and prolonged hunger, like in people who are food insecure.

Because only one of those things can be addressed with a trip to the vending machine, but both really do affect how we think. So next time you're feeling hangry, remember: it's ok to get a snack. Your future self will thank you for making the right decision.

Hey, know who makes great decisions? Our patrons. At least, in our totally unbiased opinions, supporting us is a super cool and amazing thing that they do.

Patrons help us make great videos for the whole internet, and we truly value that support. If you want to get involved, check out patreon.com/scishow. [♪ OUTRO ].