There’s a quality I’ve long appreciated in Mary Roach’s writing: humility. Her books — which include the science of sex in Bonk, the science of human decomposition in Stiff, and the science of digestion in Gulp — are not written in the voice of an all-knowing expert. Instead, her books are full of references to how ignorant she is.

Here’s a passage from her latest book, Grunt, on science in the military. She’s discussing the Stryker, a souped-up, bomb-resistant transport vehicle, with Mark Roman, who oversees their development.

… the Stryker was never a lushly appointed vehicle. There is no onboard toilet. (There are empty Gatorade bottles.) The early ones didn’t even have air conditioning. I tell Mark I’m glad to see some cup holders were left in place. I recognize the brief, polite silence that follows. It’s Mark Roman rendered mute by the fullness of my ignorance. They’re rifle holders.

In Spook, her 2006 book on how scientists have studied the afterlife, she takes pains to explain her lack of knowledge while reporting on a subject. In this passage she consults Gerry Nahum, a Stanford engineer, to analyze a soul-weighing experiment she read about:

I’ve just describes to Nahum the experiments of Duncan MacDougall [a turn-of-the-century physician who tried to weigh the escaping souls of dying patients], hoping to get his professional opinion regarding what might have caused the mysterious weight losses. A flicker of worry crosses Nahum’s brow. Before I arrive, we exchanged a few e-mails, but I failed to fully prepare him for the depths of my ignorance. My ignorance is not merely deep, it is broad; it is a vast ocean that takes in chemistry, physics, information theory, thermodynamics…

These moments give her books — which are typically about dark and uncomfortable topics — a good dose of self-effacing humor. But they are also a hugely important reporting tactic. “I own my ignorance,” Roach told me recently.

I find that empowering: To write good stories, you don’t have to be the smartest in the room — just the most curious. Not caring if others think you’re dumb means having the confidence to ask the questions essential for understanding.

In Grunt, curiosity abounds. Roach witnesses cadavers serving as test dummies to help build better IED-resistant vehicles. She shadows physicians perfecting techniques for penis transplants (you may snicker, but losing genitalia to an IED is a scar many solders have had to bear, with few options for reconstruction). She checks out a hyper-realistic battlefield simulation complete with Hollywood-level special effects. She asks military officials if diarrhea has ever been a threat to national security.

Recently I spoke to Roach by phone to learn more about her process and how she prepares for these excursions. Here’s a selection of our conversation, lightly edited for clarity and length.

Brian Resnick: Do you prepare much for your interviews?

Mary Roach: I don’t write out the questions in a formal way before I go. I have a piece of paper. On it I’ve jotted down things I really need to understand and have somebody talk to explain to me.

But I’m really letting the people, when I get there, lead me to the most interesting things. I don’t really know the best questions to ask before I get there because I really am so ignorant of the scene.

It’s not out of lack of preparation. But as soon as you arrive in a lab and step into somebody’s world of research, you just realize there’s so much more to it, and it’s different than what you thought. So I advocate not being overprepared.

“Who knows what they say behind my back when I leave? ‘Oh my god, what an idiot!’ But I don’t care.”

BR: So how do you pick what you want to report on?

MR: I’m mostly upfront looking for a scene and a setting, something I’ll be able to step into and describe. I want there to be characters and interesting characters. I haven’t met any of these people yet, so it’s a bit of a crapshoot. I don’t know what I’m getting into until I get there. I’m making a decision based on what kind of scene will this be.

[In Grunt] for a couple of chapters, I waited over a year for something to take place. It took me over a year to get on to that nuclear missile sub [chapter 13 is about how submarine sailors struggle with sleep], and it was over a year before the Aberdeen underbody blast body cadaver project got underway [in chapter two]. I knew they’d be really interesting scenes. I didn’t know what the people would be like. But I at least know there will be an interesting setting to put the science into.

BR: What are the benefits and trade-offs to not being totally prepared? How does it direct your work?

MR: When you don’t have an extensive background in a topic … you show up with a sense of wonder and curiosity, and you’re exploring something for the first time. That enthusiasm and curiosity that you bring makes it kind of fun for the researcher to be sharing this world with somebody from the outside.

The downside of it is that I’m sometimes over my head. I don’t know the science well enough to follow where [the scientists] have taken the conversation. So it’s up to me to slow them down and have them explain it to me. Or steer me to somebody else who can explain it to me.

If I had a science background, I’d know exactly what they’re talking about. It would make perfect sense. But then I would need to turn around and explain it to my reader who may not have a background. It’s helpful in that way too. I’m kind of at the same level as a lot of my readers.

I own my ignorance, if you will. I don’t have any shame anymore. I’m just like, “I’m really sorry, I know this is super basic for you, I know you can’t believe I don’t know the answer to this, but can we just go over this.’” I’m really grateful to them, and I really don’t care anymore. I don’t know if I ever did care. I’m really upfront with it.

BR: Sometimes in my reporting I’ll come across academics who say things like, “You’d need to take a whole semester course before we can talk.” I recently had a prominent psychologist write me in an email: “The average person cannot evaluate a scientific finding for themselves any more easily than they can represent themselves in court or perform surgery on their own appendix.” It can be discouraging. How do you deal with that?

MR: Those people are rare and should be avoided.

I once reported a story for Discover. It had to do with some kind of weather system on an airplane that flies into hurricanes, I had this meteorologist [who] was intentionally refusing to speak to me on a level I could understand. So I just went to the back of the plane. When I landed, I called my editor and said, “This isn’t going to work.”

First of all, the storm didn’t happen. Second, the interviewee was not willing to play ball. So forget it. Kill it.

BR: Do you think most people are generous with their knowledge?

MR: Incredibly generous and incredibly patient. Who knows what they say behind my back when I leave? “Oh, my god, what an idiot!” But I don’t care.