Coordination without communication

ABC tasked six pairs of strangers to find each other in the New York City¹. They don’t know when and where to meet or even how the others look like - no other information is provided. They were given $100 and time until the end of the day to find each other.

It sounds like an impossible task, doesn’t it?

Yet, within three hours, three groups of people found each other atop the Empire State Building, while the remaining participants reunited in Times Square!

So, in a city of millions, how did these groups—without any prior communication regarding time or location—manage to meet so quickly?

Game theory offers an explanation through the concept of coordination games.

According to game theory, in the absence of communication, people tend to put themselves in others’ shoes and try to predict how those others will act. The solutions, formally known as focal points or Schelling points, are based on cultural norms, shared knowledge or natural coordination cues.

Although the concept may sound complicated, the idea behind Schelling points is quite straightforward—at least intuitively. Faced with a problem that has a vast set of possible solutions, people naturally rely on their pre-existing knowledge to narrow down the possibilities. In this case, they use that same knowledge (and their inherent biases) to guess what others might expect them to do.

In this case, each group put themselves in the shoes of others and asked themselves “what would the other groups think we’ll do” and did that.

• They’ve picked the Empire State Building and Times Square because those are iconic meeting spots often featured in movies.
• They guessed that others would try to meet at noon rather than, say, 13:45 because 12:00 is a psychologically significant time – it’s exactly halfway through the day, symmetrical on a clock face, and universally recognized as a common meeting time for lunch or appointments.

And it worked!

A few insights about focal points

• Focal points are not universal - they depend a lot on the context (cultural, environmental, relationship, etc.).

  For example, when two riders are on a collision course - if both the riders are from right-side driving countries, each would naturally take right. If one is from a right-driving country and the other is from a left-driving country, the chances of collision increase quite a bit. Surprisingly, even when both the riders are from countries that drive on the right, when they have eye contact, the need to mirror the other person’s action increases the chance of collision.

• Focal points change based on shared knowledge or context

  When asked to pick a number in the sequence 24, 48, 100, 1024 - different people may pick different numbers. However, when asked to pick a number that others would likely pick, 100 stands out. When armed with the information that the others are predominantly programmers, 1024 (2^10) could be a focal point.

• The theory breaks down when the parties involved do not intend to coordinate. Say, two people tried the same NYC experiment and if one of them decided to just sit at their home expecting the other person to find them, then the game is going to run for a very, very long time.

A few interesting examples across different fields

• Search for Extraterrestrial Intelligence (SETI) looks for potential extraterrestrial signals on the 1420 MHz band. Why 1420 MHz? It’s the frequency of emission of neutral hydrogen, also known as the hydrogen line or 21-centimeter line. If there is an advanced civilization out there, chances are they’d know about the water hole, the importance of the hydrogen line, and they’d choose this frequency to transmit signals anticipating that other civilizations would monitor it. A Schelling point, of course.
• In business negotiations, certain numbers often become focal points. When negotiating prices, round numbers like $100,000 or $1 million often serve as anchors that both parties gravitate toward.

Schelling points reveal humanity’s instinct for collaboration through shared salience. When designing systems—whether meeting points, protocols, or social norms—leverage what’s obvious, not just optimal