The day before I was due to fly to Paris for an OECD meeting last year, I woke up feeling unwell. I'd spent months preparing for the trip and was looking forward to the meeting. As I walked to the hallway closet where we keep our COVID tests, masks, and medications, a thought flashed through my mind: What if I just didn't take the test? If I didn't test, I wouldn't have to face the possibility that a positive result would derail the trip.

I took the test. It was negative, and I boarded my flight the next day.

The hesitation lasted only a few seconds, but it left me with a question. Why had I even considered skipping the test? It wasn't the swab I minded. It was what the result might mean.

As this issue of Applied Psychology Around the World explores, that brief hesitation reflects one form of deliberate ignorance. Sometimes people avoid information because they expect it will make them anxious, guilty, disappointed, or uncomfortable. Sometimes they see little value in knowing. Sometimes, as in my case, they suspect that knowing will require them to change course. The motivations vary, but the result can be the same: choosing not to know.

The closer we come to the 2030 deadline for the Sustainable Development Goals, the more I find myself asking a simple question: Are we willing to know?

Whether we are talking about climate change, inequality, public health, decent work, or strong institutions, sustainable development depends not only on generating knowledge but also on our willingness to seek it, engage with it, and learn from it. Over the past decade, researchers, practitioners, policymakers, and communities around the world have generated an extraordinary body of knowledge about how to improve lives and strengthen societies. We know far more than we once did about improving health, reducing poverty, promoting gender equality, strengthening institutions, supporting decent work, and protecting our planet. Scientific discovery will, of course, continue.

In previous columns, I have described psychology as a Sixth P alongside the United Nations' five Ps of sustainable development: People, Planet, Prosperity, Peace, and Partnerships. Psychology belongs alongside these priorities because sustainable development ultimately depends on human behavior. People interpret evidence. People shape organizations. People design institutions. People decide whether to act on what they know. They also decide whether to find out in the first place.

Psychology has much to contribute to our understanding of how people engage with information. Decisions about whether to seek information, how to interpret it, whom to trust, and whether to avoid it altogether are shaped by emotions, identities, habits, social norms, incentives, and the environments in which people live and work.

Fortunately, psychology offers more than a diagnosis. By helping us understand why people seek out some information while avoiding other information, psychological science can also help us create conditions that encourage curiosity, openness, and learning.

As I write my final Sixth P column as IAAP President, I am more convinced than ever that psychology has an essential role to play in sustainable development. That conviction has only grown stronger over the past four years. The challenges that lie ahead are not only scientific or technical. They are profoundly human.