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The phrase rule of three is a Rorschach test. When people hear it, it can conjure an array of disparate guidelines. Celebrity deaths. Rhetorical technique. Aesthetic pleasure. Free markets. Joke writing. There are so many rules of three across disciplines and superstitions that the concept requires its own disambiguation page on Wikipedia, which lists 17 different options.

Some of those rules are more important than others. Pilots have one for landing airplanes that advises descending 1,000 feet every three miles to ensure that the plane doesn’t drop too quickly for passengers to adjust to changing cabin pressure. Outdoors-people use one as a guide for how long people can usually stay alive in extreme conditions: three minutes without oxygen, three hours without shelter, three days without water, and three weeks without food. More broadly, groupings of three pop up everywhere: the Holy Trinity, the three branches of the U.S. government, the number of data points required to determine an unknown location, the number of partners needed to corner people at a party to talk about polyamory.

Relatively little is known about why people enjoy and invoke triads so frequently. But after more than a decade of personal research, I’d like to present a new rule of three for your consideration: If you work at a desk in an office, three desk beverages is the ideal number to keep by your side. The first is water. The second is a source of caffeine. The third is something fun—a juice, a soda, a glass of wine on Friday afternoon (if your office is like that), a kombucha (if you are like that).

The case for having any beverages at your desk in the first place is one of basic human biology. Your mom was right when she told you to drink some water: Mild dehydration isn’t a notable health risk, but the spotty research done on the topic suggests that being thirsty is distracting. Slaking that thirst might help you return to your spreadsheets and get out of the office on time. Even if you’re not thirsty, people tend to report feeling more alert after having some water. Water is the foundation of your beverage kingdom.

And then there’s caffeine. Research has shown that it improves alertness in moderately sleepy people—for instance, those who underestimated the size of their sandwich and are now slowly slipping into a food coma at their desk. Maybe you stayed a little too long at happy hour last night and need a coffee to help ease your headache. Or maybe you’ve just been riding around on the planet with the rest of us for long enough that you need a Diet Coke on a spiritual level. Add it to the lineup.

Completing the desk-bev triumvirate is where the magic happens. A third beverage is your wild card, a chance for a little bit of random pleasure in a period of the day that is otherwise not your own. One of the reasons people go so wild for random snacks in the workplace is that popcorn or cookies allow a moment of disengagement from work that feels autonomous. Since water and coffee are the only drinks many workplaces provide, tracking down a third can be an excuse to leave the office for a moment, even if it’s just to run to the nearby corner store. Small, regular pleasures have real psychological value in any part of life. During the workday, acquiring a mango seltzer or green juice can return some humanity to the cubicle farm.

It probably isn’t a coincidence that three is my personal sweet spot, according to Kurt Carlson, a marketing researcher at the College of William & Mary’s Raymond A. Mason School of Business. As far as I can tell, he’s the only person who has done significant research into why and how human brains sort things into groupings of three. “People believe they’re observing something special when they see the third instance of it happen,” he explains. “After making three shots in a row, the person’s hot, and four doesn’t make them more hot. If you miss three traffic lights in a row, the world’s out to get you.”

Carlson references shots because he began his research by looking at data from the Philadelphia 76ers basketball team. He found that when players make or miss three shots in a row, both they and their competitors believe that they are on a streak, which actually changes the probability of a player making or missing the next shot. If a guy is hot, he is “going to take shots that he shouldn’t take, the defense is going to double-team him, his teammates are going to force him the ball in places they shouldn’t have forced him the ball,” Carlson explains. Counterintuitively, that makes a player with “hot hands” less likely to make a fourth shot than under baseline circumstances. The inverse also happens for players who miss three: Everyone takes that as a sign that a player is no longer a threat, and the player’s chances of sinking a shot end up improving.

When it comes time to make decisions or process new information, people often default to problem-solving shortcuts called heuristics, many of which are so ingrained in human thinking that it might feel like you were born with them. Carlson believes that groupings of three spring out of our brains’ efforts to be simultaneously organized and complete. “The least cognitively challenging way to categorize things is to put them into two buckets, and the hardest way is to treat everything as an individual,” he says. The middle-ground approach to distinguishing between concepts without driving ourselves mad with nuance is to put things into three categories. In that sense, at least, the theory of hydration, caffeine, and pleasure is time-tested and psychologically approved.

Unfortunately, academia stands in the way of testing my desk-bev theory any further. “That is as far as I got,” Carlson says. “I moved on. You can only publish so many things that are cutesy like that before you damage your reputation as a real scholar.”

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