Back in 1977, the American workplace looked very different. Divided offices were the norm. You could smoke cigarettes almost anywhere. If you were lucky, you had a mimeograph machine to make copies. Open offices? Remote work? Ping pong tables? Yeah, right.

That same year, Thomas J. Allen studied how proximity influences communication at work. The results were striking: People were four times more likely to communicate with a coworker who was 6 feet away vs. someone 60 feet away. They almost never talked to coworkers on separate floors or in separate buildings.

The workplace has changed considerably but the “Allen Curve” is still relevant—even in the era of Slack. Open floor plan offices have been the cause of much gnashing of teeth for modern office workers, but experts agree that proximity is crucial to communication and collaboration, and its most effective form is still face-to-face.

What Thomas Allen’s research shows us is it’s not about open or closed offices—but how to effectively use space to drive collaboration.

Why “Collisions” Are Crucial

A major online travel company employing thousands of software developers was curious why some developers were performing better than others. So they consulted with MIT researcher Ben Waber who found a simple answer: lunch.

Waber explains that the company had a large cafeteria with varying table sizes. Near one entrance were tables for 12 people. Near the other entrance were tables for four. The software developers who sat at the large tables—and ate with large groups—had 10% fewer mistakes in their code than those who ate at smaller tables.

Why? Because software development is heavily dependent on the work of other team members. The large lunch tables created “collisions,” unplanned interactions between coworkers that lead to increased communication and camaraderie. Those who communicated more frequently—even lunchroom talk about Game of Thrones or dinner plans—led them to talk more about the code they were writing too.

“These seemingly inconsequential decisions about how big lunch tables are or where certain groups are located have such a huge impact on how we work and collaborate,” says Waber, who’s now CEO and co-founder of people analytics software firm Humanyze. “Today, they are just so unoptimized. It gets to the point where, literally, the company duct-taped tables together.”

Radical Collocation at Ford, Quick Problem-Solving at Boeing

The intersection of proximity and communication at work isn’t just predicated on creating collisions—it’s about using space to help drive desired behavior.

Take the case of Ford Motor Company in the late 1990s. The company was hoping to increase productivity among its software engineers, so it partnered with Judith Olson, a distance-work expert at the University of California at Irvine. She placed teams of six to eight software engineers into “war room” style workspaces sequestered from the rest of the workforce. Developers had a peripheral awareness of what coworkers were working on and could chime in when they tried to solve complex problems. The concept is called “radical collocation,” and the results were astounding: The teams doubled their productivity and finished projects in about a third of the time.

The productivity gains were directly related to the workspace design. “Workers knew when not to disturb somebody—and when to jump in and help,” says Olson.

Perhaps the most poignant example of the power of workplace proximity took all of 24 seconds. It took place in the cockpit of a simulated flight of a Boeing 727—and it led to a fascinating analysis by researchers at UC San Diego and UC Irvine.

One of the three crew members noticed a fuel leak. Without saying much more than “ooh” and “hmm” the crew members used non-verbal cues (like the flight engineer jabbing his finger at the fuel gauge) to communicate, diagnose, and fix the problem.

Imagine if those pilots were communicating via Skype or email? Or if they had to check each other’s schedules, then send out a meeting request? It would likely have taken dozens of messages, wasted plenty of time, and might not have been resolved before the fuel tank was empty. Not a recipe for success.

Not the people you want communicating via email chain.

“There are about 100 things that happen when you’re face-to-face that don’t happen when you’re long distance,” says Olson. “The number of cues you get about what the other person is thinking is extraordinary. What their hands are doing, whether they’re looking at you, their body distance—it’s all crucial.”

So should we just design open offices and master the art of proximity and work? Not exactly.

“In too many open offices, employees are too close to each other. Everybody is on headphones so what’s the point?” says Olson. In her view, coworkers should be about 10 feet from one another in open offices. That’s just enough space to allow people to feel comfortable, still see what co-workers are up to in the periphery, but not invade personal space.

Working remotely or in different offices is also a necessity. But despite all the technology at our disposal, people are still more likely to talk digitally with people they frequently see face-to-face. In fact, Waber studied a group of engineers and found that those who shared a physical office were 20% more likely to communicate digitally compared to coworkers located elsewhere. Collocated colleagues emailed four times as frequently as those in different locations—leading to project completion times that were 32% faster.

“The fact that I have pre-existing relationship with you, means it’s much more likely that I’ll email you compared to people I never see face-to-face,” says Waber.