Five is the magic number of people for making Zoom calls effective — a professor and teamwork expert explains why

• John R. Hollenbeck is Michigan State University professor who has conducted extensive research on leadership and teamwork.
• He says large meetings over Zoom are ineffective, and more than just for technical reasons.
• To make your meetings more useful and engaging, limit them to groups of five, and break your company into a multi-team structure.
• You should also consider who really needs to be participating in meetings and email chains.
• Visit Business Insider's homepage for more stories.

As workplaces across the country have gone virtual, people are feeling the strain of wading through endless video meetings and email chains. Maybe the connection is glitchy, your colleague doesn't understand the power of the mute button, or you're caught in a "reply all" rabbit hole. But even when the tech and etiquette are operating perfectly, there's a much more fundamental problem at play: Humans simply weren't designed for a 15-person Zoom meeting.

There's a basic tenet among those of us who study management that big teams are bad teams. Effective communication and coordination begin to break down in groups larger than five. This has always been true, it's simply more obvious in the virtual world because the non-verbal cues that help us slide by in large face-to-face meetings have been snatched away.

You can make your organization's virtual communication less painful by understanding and working within our human cognitive limits. This requires being disciplined about who is included in every meeting and team, implementing clear leadership roles, and having explicit guidelines for how communication should operate in the virtual world.

Why 5 is the magic number

After conducting a series of experiments with different size teams, social psychologist J. Richard Hackman identified 4.6 as the optimal size for a well-functioning team. (He allowed that this number can increase slightly if the people involved have a great deal of experience working together and thus many things can "go without saying.")

The enemy of large teams is the number of communication links that have to be managed. As team size grows linearly, the links among team members grow exponentially. A five-person team has to manage 10 links, while a 10-person team has to manage 45. And a 15-person team? Forget about it: 105 links.

Thus, a growing team quickly bumps against the limits of our human capacity for communication. We simply didn't evolve to be able to effectively communicate with 10 or 20 people at one time. There are also limits on the total number of people we can maintain social relationships with across all areas of our lives. After studying primate social groups and traditional human tribes, anthropologist Robin Dunbar determined that our brains can't manage more than 150 stable social relationships, a constraint known as "Dunbar's number." In the modern world, this capacity is divided across numerous professional and personal networks.

The power of multi-team systems

Does this mean we can never have a business unit bigger than five or an organization larger than 150? Of course not. It's not the absolute size of a group that matters, it's about how we organize individuals and the communication links among them.

For instance, if you have a 25-person engineering team, you can split them into pods of five. Communication across pods happens among the five leaders of each pod, who then share relevant information back with their respective groups. This structure creates just 10 communication links within each of the sub-teams and roughly 15 links for members of the leadership team to manage, compared to 300 links in a 25-person team!

This structure is called a multi-team system and it's been very successful across a wide range of organization types. Much of my research on teamwork and multi-team systems has been funded by the Department of Defense and the National Science Foundation. Even though military operations and large collaborative science efforts are very different tasks, the multi-team system structure works well in both contexts. It allows for a super-team with large size and scope, and thus extensive expertise, while at the same time limiting the number of communication links that have to be managed.

In his book "Teams of Teams," General Stanley McChrystal, the former leader of US forces in Afghanistan, describes how multi-team systems have been employed in counter-terrorism efforts. For example, the hunt for Osama bin Laden initially involved several giant elephants — including the CIA, the FBI, the State Department, and multiple branches of the military — all trying to catch a mouse by blanketing the mountains of Afghanistan with bombs. Success only came when the military created a nimble multi-team system, drawing members and expertise from many of these organizations but operating outside their normal hierarchies. Ultimately, bin Laden was killed by a small team of Navy Seals in a well-planned raid that lasted less than an hour.

Escape video-call misery

As the military discovered, multi-team systems are project-based and can be layered on top of existing hierarchies. You don't have to completely reimagine your organizational structure, especially in a chaotic moment like the one we are currently facing. You can reap many of the benefits of multi-team systems right now by creating clear structures and rules for communication when working remotely.

The most important rule is to never have a meeting with more than five people. The reasons will be obvious to anyone who's ever tried to awkwardly figure out whose turn it is to speak during a large videoconference, but it also holds true for face-to-face meetings. Sticking to the five-person limit can feel hard, but it forces you to think carefully about how your team members interact and who actually needs to be in a particular meeting.

This doesn't mean you can't host a virtual gathering of more than five people. There may be times leaders need to communicate information to a large number of people at once through a one-way broadcast, or a small group of leaders engaged in a discussion may want their team members watching over their virtual shoulders with the mute button on. As I mentioned earlier, it's about the number of communication links happening, not necessarily the total number of people observing the collaborative process.

Every virtual meeting should have a clear agenda and norms for how communication will rotate. Without non-verbal cues, it's much harder for people to know when to step in and talk. Leadership roles should be clear, including the formal leader, aka the boss; a technology leader managing meeting logistics; and the information leader who is sharing information on a given topic (this position often rotates over the course of a meeting).

These guidelines don't just apply to virtual meetings. We've all been caught in a nightmarish reply-all email thread or CC'ed on a communication that was barely relevant. You can avoid wasting people's time by establishing clear norms and expectations about who should be looped into various conversations and who is expected to pass along essential information to those who are not part of a discussion.

Learning from exceptional circumstances

We're still adapting to a massive disruption in our normal professional lives and it's no surprise that our virtual communication is a work in progress, especially given that our face-to-face communications could stand to improve too. But it may help to know that there's a reason your 15-person Zoom meeting feels like such a slog – we just weren't wired to communicate that way.

The good news is that you can implement simple solutions that don't require new technology or a shake-up of your entire org chart. You can see big gains in efficiency and morale by layering a multi-team system for communication on top of your existing structures and outlining clear processes and expectations for how communication should flow.

We might even find the stresses of virtual communication offer an opportunity that forces us to be more thoughtful about how we're communicating in general. Hopefully there are some lessons and systems we can carry forward into our normal operations, since this is how we should have been doing things all along.

John R. Hollenbeck is University Distinguished Professor at Michigan State University and the Eli Broad Professor of Management at MSU's Eli Broad College of Business. He has conducted extensive research on leadership and teamwork, much of it funded by the US Department of Defense and the US National Science Foundation.