Diversity and team performance: What the research says

(Photo of group of people doing a hard thing from Wikimedia user Rizimid, CC BY-SA 3.0.)

This is an extended version (more info, more sources) version of the talk I gave at EA Global San Francisco 2017. The other talk I gave, on extinction events, is  here. Some more EA-focused pieces on diversity, which I’ve read but which were assembled by the indomitable Julia Wise, are:

Effective altruism means effective inclusion

Making EA groups more welcoming

EA Diversity: Unpacking Pandora’s Box

Keeping the EA Movement welcoming

How can we integrate diversity, equity, and inclusion into the animal welfare movement?

Pitfalls in diversity outreach


There are moral, social, etc. reasons to care about diversity, all of which are valuable. I’m only going to look at one aspect, which is performance outcomes. The information I’m drawing from here are primarily meta-studies and experiments in a business context.

Diversity here mostly means demographic diversity (culture, age, gender, race) as well as informational diversity – educational background, for instance. As you might imagine, each of these has different impacts on team performance, but if we treat them as facets of the same thing (“diversity”), some interesting things fall out.

(Types of diversity which, as far as I’m aware, these studies largely didn’t cover: class/wealth, sexual orientation, non-cis genders, disability, most personality traits, communication style, etc.)

Studies don’t show that diversity has an overall clear effect, positive or negative, on the performance of teams or groups of people. (1) (2) The same may also be true on an organizational level. (3)

If we look at this further, we can decompose it into two effects (one where diversity has a neutral or negative impact on performance, and one where it has a mostly positive impact): (4) (3)

Social categorization

This is the human tendency to have an ingroup / outgroup mindset. People like their ingroup more. It’s an “us and them” mentality and it’s often totally unconscious. When diversity interacts with this, the effects are often – though not always – negative.

Diverse teams tend to have:

  • Lower feelings of group cohesion / identification with group
  • Worse communication (3)
  • More conflict (of productive but also non-productive varieties) (also the perception of more conflict) (5)
  • Biases

A silver lining: One of these ingrouping biases is the expectation that people more similar to us will also think more like us. Diversity clues us into diversity of opinions. (6) This gets us into:

Information processing 

Creative, intellectual work. (7) Diversity’s effects here are generally positive. Diverse teams are better at:

  • Creativity (8) (2)
  • Innovation (9)
  • Problem solving. Gender diversity is possibly more correlated than individual intelligence of group members. (Though this conclusion might have failed to replicate. Taymon Beal kindly brought this to my attention after the talk, and I’ve only skimmed it since, but you may want to look into it.) One of the factors implicated is more equal distribution of who’s talking (observed in ethnically diverse groups as well.) (10)
  • Decision-making (15)

Diverse teams are more likely to discuss alternate ideas, look at data, and question their own beliefs.


This loosely maps onto the “explore / exploit” or “divergent / convergent” processes for projects. (2)

    1. Information processing effects benefit divergent / explore processes.
    2. Social categorization harms convergent / exploit processes.

If your group is just trying to get a job done and doesn’t have to think much about it, that’s when group cohesiveness and communication are most important, and diversity is less likely to help and may even harm performance. If your group has to solve problems, innovate, or analyze data, diversity will give you an edge.


How do we get less of the bad thing? Teams work together better when you can take away harmful effects from social categorization. Some things that help:

    1. The more balanced a team is along some axis of diversity, the less likely you are to see negative effects on performance. (12) (7) Having one woman on your ten-person research team might not do much to help and might trigger social categorization. If you have five women, you’re more likely to see benefits.
    2. Remote teams are less biased (w/r/t gender). Online teams will be less prone to gender bias.
    3. Time. Obvious diversity becomes less salient to a group’s work over time, and diverse teams end up outperforming non-diverse teams. (13) (6) Recognition of less-obvious cognitive differences (e.g. personality and educational diversity) increases over time. As we might hope, the longer a group works together, the less surface-level differences matter.

This article has some ideas on minimizing problems from language fluency, and also for making globally dispersed teams work together better.


How do we get more of the good thing? Diversity is a resource – more information and cognitive tendencies. Having diversity is a first step. How do we get more out of it?

    1. At least for age and educational diversity, high need for cognition. This is the drive of individual members to find information and think about things. (It’s not the same as, or especially correlated to, either IQ or openness to experience (1)).

Harvard Business Review suggests that diversity triggers people to stop and explain their thinking more. We’re biased towards liking and not analyzing things we feel more comfortable with – the “fluency heuristic.” (14) This is uncomfortable work, but if people enjoy doing it, they’re more likely to do it, and get more out of diversity.

But need for cognition is also linked with doing less social categorization at all, so maybe diverse groups with high levels of this just get along better or are more pleasant for all parties. Either way, a group of people who really enjoy analyzing and solving problems are likely to get more out of diversity.

2) A positive diversity mindset. This means that team members have an accurate understanding of potential positive effects from diversity in the context of their work. (4) If you’re working in a charity, you might think that the group you might assign to brainstorming new ways to reach donors might benefit from diversity more than the group assigned to fix your website. That’s probably true. But that’s especially true if they understand how diversity will help them in particular. You could perhaps have your team brainstorm ideas, or look up how diversity affects your particular task. (I was able to find results quickly for diversity in fundraising, diversity in research, diversity in volunteer outreach… so there are resources out there.)


Finally, diversity’s effect size on innovation isn’t huge. It’s smaller than the effect size support for innovation, external and internal communication, vision, task orientation, and cohesion – all these things you might correctly expect correlate with diversity more than diversity (15). That said, I think a lot of people [at EA Global] want to do these creative, innovative, problem-solving things – convince other people to change lives, change the world, stop robots from destroying the earth. All of these are really important and really hard, and we need any advantage we can get.


  1. Work Group Diversity
  2. Understanding the effects of cultural diversity in teams: A meta-analysis of research on multicultural work groups
  3. The effects of diversity on business performance: Report of the diversity research network
  4. Diversity mindsets and the performance of diverse teams
  5. The biases that punish racially diverse teams
  6. Time, Teams, and Task Performance
  7. Role of gender in team collaboration and performance
  8. Team-level predictors of innovation at work: A comprehensive meta-analysis spanning three decades of research
  9. Why diverse teams are smarter
  10. Evidence of a collective intelligence factor in the performance of human groups
  11. When and how diversity benefits teams: The importance of team members’ need for cognition
  12. Diverse backgrounds and personalities can strengthen groups
  13. The influence of ethnic diversity on leadership, group process, and performance: an examination of learning teams
  14. Diverse teams feel less comfortable – and that’s why they perform better
  15. Team-level predictors of innovation at work: A comprehensive meta-analysis spanning three decades of research
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