Complementarity as the holy grail: on the gap between ideal and practice

For a long time, teams unconsciously favoured people who resembled the leader. This tendency is known as similarity bias or affinity bias. As this pattern became more visible, awareness grew that homogeneous teams carry a blind spot. The counterargument gained ground: seek people who complement, challenge, and think differently from yourself. Complementary teams are now widely regarded as a prerequisite for sound decision-making and resilience, particularly in times of uncertainty.

In our interview series with leaders on successful leadership in uncertain times, this view came through clearly. Sven Sauvé put it as follows: "Ten years ago I would probably have surrounded myself with five lookalikes, nice and easy to work with. Now I have as many different personalities and backgrounds in my team as possible. In my view, that makes decision-making so much better." Mark Siezen describes effective leadership in similar terms: "not being the one who does everything best or knows the most, but the one who recognises those qualities in others and brings them together."

The ideal is widely embraced. In principle, it holds up. But there is another question that is asked too rarely. Are the conditions needed to realise that ideal receiving sufficient attention?

What the research shows

This question is not new. In 2007, Van Knippenberg and Schippers published a literature review on the relationship between team diversity and team performance. Their conclusion was more nuanced than the prevailing view: diversity does not automatically lead to better outcomes. The effect depends on what they call the elaboration of task-relevant information, the extent to which team members exchange, process, and integrate different information and perspectives in collective decision-making.

Nearly two decades later, research still points in the same direction. Wallrich and colleagues analysed the results of 615 studies in 2024 and reached a similar conclusion. The relationship between diversity and team performance is positive, but limited. They also established that the field has still not succeeded in clarifying under which circumstances diversity does or does not work.

The potential of the complementary team has long been recognised. What is needed to actually realise that potential remains insufficiently understood.

Why complementarity fades in everyday practice

In conversations with leaders and candidates, we strongly recognise the ideal of complementarity. The image of a team as the sum of different perspectives, styles, and backgrounds is appealing and embraced almost without exception. Complementarity functions as a kind of holy grail, something to strive for in order to reach better decisions.

At the same time, practice tells a different story. Having a complementarily composed team is fundamentally different from making use of complementarity. The latter requires skills and habits that receive far less consistent attention: the ability to genuinely challenge one another, space for different paces and thinking styles, empathy, and an open outlook.

What we frequently observe is that leaders organise diversity at the level of composition, but not at the level of interaction. Difference is welcome, as long as it does not create too much friction. As soon as perspectives genuinely clash or slow things down, the tendency arises to fall back on like-minded colleagues, familiar patterns, or quick consensus. Precisely where complementarity could add value, it is smoothed away in practice.

This rarely happens out of unwillingness. It happens because the everyday logic of a team works against sustaining difference. There is a need for progress. A meeting agenda has an end. A decision must be made. Someone who consistently slows things down or asks questions is quickly perceived as an obstacle. The cost of deviation rises, even when no one explicitly names that cost.

What happens under pressure

Precisely at the moment when complementarity is most needed, the conditions to make use of it prove most fragile. Under pressure, attention shifts almost automatically — from process to outcome, from dialogue to decision, from nuance to speed. What was previously seen as valuable difference quickly comes to be experienced as noise or risk.

An example we encounter regularly. A leadership team is under time pressure to make a strategic choice. One member raises a fundamental objection — substantively valid, but poorly timed. The chair sets it aside with a promise to return to it later. The decision is made. That later never comes. The team member learns that dissenting in this setting yields little and adjusts accordingly next time. The team loses not a member, but a voice.

Mark Siezen's quote touches on this tension. By organising, outside the formal structures, a partner who is not easily impressed and who confronts him daily, he implicitly acknowledges how vulnerable dissent within teams can be. In practice, dissent requires protection — not because people are unwilling, but because the social and emotional costs of deviating increase under pressure.

Teams that manage to sustain complementarity under pressure rarely do so on the basis of natural ability. It is the result of deliberate choices and repeatable habits.

Three preconditions that make the difference

Which preconditions come up repeatedly in our conversations with teams that do manage to sustain complementarity?

The first is explicitly naming what kind of difference is needed right now, not diversity in a general sense, but the specific perspective that is missing from this particular decision. Who is thinking from a risk angle? Who from the client's perspective? Who from a long-term view? By naming the difference, it becomes discussable.

The second is protecting the minority voice. This is a role, not a coincidence. In effective teams, someone consistently takes on the task of surfacing the dissenting voice, repeating it, and ensuring it lands in the decision-making process. Often that is the chair, but the role can also be explicitly assigned to another team member.

The third is normalising tension. In teams that handle this well, the discomfort of difference is not a signal that something is going wrong. It is a signal that the work is being done. Chairs who can tolerate this, and who name it out loud when a conversation creates friction, give their team permission to press on rather than retreat.

These preconditions are not complicated. They require no restructuring and no additional role. What they do require is a willingness to organise temporarily against the pressure, to keep making room for dissenting perspectives, even when those perspectives are uncomfortable or slow down the decision-making process.

In closing

Complementarity is not a characteristic of a team. It is the outcome of behaviour — the ability and willingness to actively seek out one another's perspectives, even when that is uncomfortable. This demands something of individuals, but above all of the context in which they work.

The question is not how to compose a complementary team. Leaders already ask themselves that question. More relevant is what conditions are needed for such a team to function as intended — and how those conditions hold up when pressure increases.

This is a pattern that Sebijn Bunt recognises in her daily conversations with leaders, candidates, and clients. The ambition to work together in a complementary way is widespread. The preconditions to make that a reality are far less so. That, in our view, is where the real conversation lies.

Curious about what this looks like in practice? Get in touch!