As someone who completed my junior independent work under Professor Walker’s guidance last semester, I’ve had the chance to witness his thoughtful mentorship firsthand. In a research culture where both the technical challenge and emotional uncertainty can feel overwhelming, I’ve come to appreciate how crucial the human side of research is—how we learn from and grow with those who guide us. With that in mind, I sat down with Professor Walker to explore how he thinks about mentorship: what it looks like, why it matters, and how he helps students, like me, find their footing in the world of research.
Shannon Yeow (SY): How would you describe your overall philosophy or approach to mentoring students specifically in research?
David Walker (DW): I start by getting to know who they are and what they’re interested in. At the beginning, it’s hard for students to pick a research topic because they don’t have much experience, so I’ll usually suggest a problem I’ve been thinking about. I like to give them something I’ve got a good sense of, including tools that might help them solve it.
But in some ways, the exact problem doesn’t matter. Whatever it is, the student will start learning how to define questions, how to solve them, and how to communicate what they’ve done. Half of research is problem-solving, and the other half is figuring out what question to even ask in the first place. It’s important for students to see that it’s okay for the question to shift. It might even be a good idea for the question to shift as it might’ve been too broad, too hard, or solved. That evolution is part of the process.
Initially, I’m more hands-on, supplying problems and guidance. But over time, I want students to start selecting their own problems and eventually know more than I do about their area. That’s when they’re really ready to choose a problem, solve it, and explain it to others.
SY: What do you see as the most important qualities of an effective research mentor?
DW: Time. Spending time with your students is the most important thing. That’s how you really teach someone, through conversation or through example. If I were a student picking an adviser, I’d look for someone who has time to meet with me and who has lots of ideas.
SY: How has your approach to mentorship evolved over the years?
DW: I’m not sure it’s evolved radically, but I’ve certainly learned things. One thing you come to realize is that every student is different and you can’t control them. You can nudge them, suggest things, but they won’t always take your advice, and sometimes, they’re right not to.
We recently had a faculty meeting about giving feedback. One big takeaway for me was how important it is to give specific feedback, both positive and critical. It’s easy to say, “This is wrong,” and point to an error. It’s harder to say, “This was great,” and explain why in a way that’s genuinely useful. I’m still learning how to do that better.
Emotionally, research is hard. There’s a lot of uncertainty. You don’t always know what questions you’re answering or whether they’re even good questions. So emotional support matters too, but that’s something advisers aren’t always trained in and is just hard for anyone to get right.
SY: How do you balance giving guidance while also encouraging independence and ownership?
DW: Early on I offer more guidance. Students often don’t know how to choose solvable problems or make progress. But as they do more example projects, the hope is they begin to recognize patterns and gain confidence. Eventually, I can take a lighter touch, and they lead the way.
SY: What’s been one of the most rewarding mentorship experiences you’ve had?
DW: They are all rewarding. Students can evolve so much and at different levels. When I taught COS 333, I watched students go from not knowing how a web app works to building amazing tools that help real people in the community. That’s hugely rewarding. One Ph.D. student I worked with took it a step further. While we were working on verifying some networking infrastructure, he independently formalized all our hand-written proofs in the Lean theorem prover. He didn’t even tell us. He just showed up one day with everything coded and verified. It really elevated the project and showed what happens when a student takes initiative and goes beyond what’s expected.
SY: What advice would you give to someone who is just beginning to mentor others in research?
DW: Don’t take on too many mentees too quickly. It takes time and thought to mentor well, and you’re learning too. Start slow, then expand as you get more comfortable. Talk to colleagues for advice constantly. Keep learning, no matter where you are in your career.
SY: How do you hope your mentees carry forward the lessons they’ve learned from you?
DW: I hope they help the next generation. I’ve had mentors who made a huge difference in my life, like Greg Morrisett at Cornell or Frank Pfenning and Robert Harper at Carnegie Mellon. People like that help you so much, and there’s no real way to pay them back. But you can pay it forward by mentoring others, by passing on what you’ve learned. That’s what I try to do, and I hope my students do the same.
Interview responses have been edited for clarity and length.
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Completing my independent work under Professor Walker gave me a new lens through which to understand research, not just as a technical challenge, but as a human journey. His mentorship taught me that asking the right question is just as valuable as solving one, and that intellectual independence is something developed gradually, with patience and care.
If you’re curious about research, I hope this interview offers insight into the kind of support that exists here at Princeton and encourages you to seek out mentors who will help you grow not just as a researcher, but as a thinker and a person.
— Shannon Yeow, Engineering Correspondent
