Interview with Hans Rocha IJzerman

Behavioural Science is a rapidly expanding field and everyday new research is being developed in academia, tested and implemented by practitioners in financial organisations, development agencies, government ‘nudge’ units and more. This interview is part of a series interviewing prominent people in the field. And in today's interview the answers are provided by Hans Rocha IJzerman. Hans is a Dutch psychological scientist and former basketball player dedicated to the advancement of open science and the rigorous study of social connection. As the author of Heartwarming, Hans has explored the fundamental role of warmth and human connection in shaping our lives, earning him recognition as a leader in the study of social relationships. He co-founded initiatives such as In-Mind Magazine, the Psychological Science Accelerator, and the Collaborative Replications and Education Project, each reflecting his commitment to transparency and collaboration in scientific research. His academic journey took him from St. Vincent College to Vrije Universiteit Amsterdam and Utrecht University, and he has been an influential force in advancing behavioral science reform. Hans’s work bridges the academic and public spheres, and he frequently shares insights with broader audiences through media like The New York Times, Huffington Post, and Psychology Today. Now at Annecy Behavioral Science Lab, he focuses on developing innovative tools for measuring and enhancing social connection, all while mentoring a new generation of scientists dedicated to impactful, ethical research.

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Who or what got you into behavioural science?

I found my way into behavioural science by coincidence. I left the Netherlands at 18 to pursue basketball in the United States, aiming for a professional career in Europe. While studying communication science and Spanish at St Vincent College, a psychology teacher, Miss Kerr, fascinated me with psychology. After her class, I switched my major to psychology, and that’s how it started. Being at a Catholic, Benedictine college as an atheist also influenced my interest in community, which later shaped my research focus on loneliness and attachment theory.

What is the accomplishment you are proudest of as a behavioural scientist? And what do you still want to achieve?

One of the accomplishments I’m proudest of is my current project on social connection, which involves five countries—India, Zimbabwe, Morocco, the Philippines, and Brazil. This study aims to redefine social connection by gathering perspectives directly from people in each country before developing measurement tools. Rather than imposing Western definitions, we’re asking people what social connection means to them in their own context, and we’re capturing data from diverse groups, including rural and urban populations, young and old, and those who feel isolated or connected. This project is exciting because it’s a real effort toward making research more representative and inclusive. It’s still ongoing, but I’m eager to see the cultural variations that emerge, which can challenge and enrich how we understand social connection globally.

Looking ahead, I want to push this further by personalising measurement. Humans are diverse, and we experience things like loneliness and social connection differently depending on our age, culture, or even where we live. I believe our measurement tools need to reflect this diversity. For example, how someone experiences connection in rural India may be vastly different from someone in an urban setting in Brazil. By developing more nuanced and adaptable tools, we can better understand these differences, leading to more accurate data.

This idea of personalised measurement is something I also see as crucial in areas like mental health. Right now, we often use rigid tools to assess conditions like depression or anxiety, but these experiences can vary widely across individuals. If we can personalise the way we measure these issues, we can improve not only our understanding but also how we develop interventions. Ultimately, my goal is to lay a better foundation for personalised, culturally sensitive interventions that address the real needs of different populations, starting with better measurement practices.

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What are the greatest challenges being faced by behavioural science, right now?

One of the biggest challenges facing behavioural science right now is the need to improve our incentive structures, at least in academia, where I am familiar with. For years, we've been talking about the need for better practices—things like replication, pre-registration, open data, and improving the quality of research rather than just focusing on the quantity of publications. But even though these ideas have been around for more than a decade, we haven’t fully integrated them into our incentive systems. Who gets jobs, promotions, or grants still often depends on the number of papers published, not on the quality of the research or the robustness of the methodology.

This is particularly frustrating because, as a field, we know the elementary aspects that need to change, but we're not doing enough to actively promote those changes, let alone pushing through even more complex reforms to promote research quality. Universities and funding bodies need to adjust their priorities to reward behaviours that lead to better science, such as sharing data, pre-registering studies, and focusing on replication. We’re lagging behind, and part of that is because the older structures in academia resist change. The replication crisis and push for open science have shown that many of the studies we rely on have significant issues, yet the incentive structures haven't caught up.

Another major – and long-known -- challenge is representation. Much of the research in behavioural science is still dominated by – for lack of a better term -- the Global North, which leads to findings that aren’t necessarily generalizable to the rest of the world. There are huge gaps in representation, and without including diverse populations, we’re missing out on important insights about human behaviour. This is especially critical in areas like social connection or mental health, where cultural differences can significantly shape experiences and outcomes.

Political instability and lack of resources in many parts of the world also pose challenges for expanding representation in research. Many researchers in the Global South face significant barriers, such as limited access to funding or difficulty attending international conferences due to visa issues. While there are small ways we can mitigate some of these challenges—such as promoting online conferences and providing small grants to support participation—there’s still a lot of work to be done to make behavioural science more inclusive.

Ultimately, if we don’t address both the incentive structure and representation issues, we risk continuing to produce research that is neither fully accurate nor applicable to diverse populations.

How do you think behavioural science will develop in the next 10 years?

Looking ahead, I think the development of behavioural science over the next 10 years will largely depend on how well we adapt our approaches to prioritize better research practices and representation. Right now, a lot of emphasis is placed on replication, open science, and improving the quality of our research, and I believe that will continue to grow. However, we need to move beyond the basics of just replicating studies or pre-registering experiments. One focus I personally would want to promote is a shift  toward creating more personalized and contextually relevant measurements and interventions.

For example, the way we measure things like social connection or mental health varies significantly across cultures, and a one-size-fits-all approach isn’t effective. I hope we’ll see an increased use of ethnographies and qualitative research methods to better understand how different populations experience the same concepts. This requires moving away from a reliance on standard measures developed in Global North populations and toward more inclusive and culturally sensitive methodologies. We’ll need to incorporate more diverse populations and approaches in our research design.

Another major area for development is the integration of technology, particularly AI and large language models. There’s a lot of potential to use these technologies for scaling research, whether it’s through chatbots conducting surveys or using AI to analyse large datasets. This could allow us to move beyond simple Likert scales and into more conversational or naturalistic forms of data collection, which might give us richer insights into human behaviour.

In short, the future of behavioural science should be focused on making our measurements more personalized, our methods more inclusive, and our use of technology smarter. If we can do that, we’ll not only improve the accuracy of our findings but also make the field more relevant across different contexts and cultures.

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What advice would you give to young behavioural scientists or those looking to progress into the field?My main advice for young behavioural scientists is to be proactive and strategic in navigating the field. First, focus on mastering the core skills of the discipline—statistics, programming, and research methods—but don’t stop there. The field is evolving, so understanding emerging topics like AI, machine learning, and how they apply to behavioural science will give you a competitive edge. Build your expertise in these areas, as they are becoming more integral to research and industry applications.

Another key piece of advice is to network and find good mentors. Who you work with can have a massive impact on your career trajectory. Look for mentors who are not only successful but also aligned with your values and research interests. They can provide guidance, help you avoid common pitfalls, and connect you with opportunities you might not otherwise have.

It’s also important to be open to collaboration. Behavioural science is interdisciplinary, and you’ll likely work with people from fields like economics, sociology, or data science. The ability to collaborate effectively across disciplines will broaden your research and make it more impactful.

Lastly, remain curious and passionate about understanding human behaviour. The field can be competitive, and research often moves slowly, so perseverance is key. Focus on the areas that genuinely interest you, as this will sustain you through the inevitable challenges you’ll face.

What skills are needed to be a behavioural scientist?

To become a top behavioural scientist, a combination of technical and soft skills is essential. On the technical side, strong quantitative skills are crucial, particularly in statistical analysis, programming (e.g., R or Python), and psychometrics. Being able to analyse data accurately and understand complex statistical methods helps you derive meaningful conclusions from your research. Additionally, qualitative skills are equally important, especially in projects that involve ethnographies or interviews. Understanding how to collect, analyse, and interpret qualitative data gives you a more holistic view of human behaviour, particularly across diverse populations. If you are able to master these skills, you will probably be better trained than most in the field, at least better trained than me.

Soft skills are just as important. Collaboration is a must since much of the work involves interdisciplinary teams or cross-cultural projects and I feel I have learnt a lot through Big-Team Science. Good communication skills are essential for translating complex findings into actionable insights for policymakers, businesses, or the general public.

Finally, curiosity and adaptability are vital. The field is constantly evolving, so being open to new methods, technologies, and perspectives will keep your research relevant and impactful.

Overall, the ideal behavioural scientist is analytical, flexible, and able to bridge the gap between theory and practice while also considering diverse perspectives and global representation.

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What is your biggest frustration with the field as it stands?

My biggest frustration is that we’ve been aware of the issues with replication, open science, and data sharing for years, but the field still hasn’t fully embraced the necessary changes. Grant organisations (with the exception of the EU perhaps) and universities still don’t mandate basic open science practices like pre-registration or data sharing, which would significantly improve the quality of research. I’ve trained my students to follow these practices, and while they produce good work, they might not get as many publications or jobs as those who don’t follow open science. That feels very unfair, and it’s frustrating to see older academics resist changes that could improve the field for everyone.

If you weren’t a behavioural scientist, what would you be doing?

If I hadn’t gone into behavioural science, I think I’d have pursued international relations, possibly as a diplomat. I’ve always been fascinated by international politics, and I was close to going to Cuba for the International Conference of Catholic Bishops. I was also looking at Georgetown for a master’s degree in international relations. The job in Cuba didn’t work out for pretty random reasons, but I can still see the close link between the two fields, especially with my work now with organisations like WHO and the European Union.

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How do you apply behavioural science in your personal life?

I apply attachment theory to both my personal relationships and raising my two children. Understanding felt security and the underlying, or primary, emotions when someone is upset (the secondary emotions, as an EFT therapist would have it) —whether it’s my partner or my daughter—helps me better respond and maintain strong bonds. I think attachment theory is one of the better frameworks we have, especially for relationships and parenting. It’s not always applicable across cultures, but in the Global North, it works pretty well.

Which other behavioural scientists would you love to read an interview by?

There are a few people I think are worth hearing from. My PhD supervisor, Dov Cohen, who is a cultural psychologist, would be fascinating. Brian Nosek or Simine Vazire, for their work in driving the open science movement. Alan Fiske, a cognitive anthropologist, is one of the most inspiring people I’ve gotten to know throughout my career. His relational model theory and his book, Virtuous Violence, are great contributions to understanding interpersonal relationships and violence. He’s also been a personal inspiration throughout my career, especially during more challenging periods.

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Thank you so much for taking the time to answer my questions Hans!

As I said before, this interview is part of a larger series which can also be found here on the blog. Make sure you don't miss any of those, nor any of the upcoming interviews!

Keep your eye on Money on the Mind!