You may know Joe Palca as one of the voices of science on National Public Radio. Over his nearly two decades at NPR, he's covered topics as diverse as space shuttles, medical research and basic physics. But before he became a science journalist, Palca spent several years as a sleep researcher and earned a PhD in psychology at the University of California–Santa Cruz.

Now, in his first book "Annoying: The Science of What Bugs Us," Palca has returned to his behavioral science roots. He and co-author Flora Lichtman, multimedia editor at NPR's "Science Friday," tackle a universal but perhaps understudied topic: annoyance. Palca and Lichtman talked to psychologists, neuroscientists and other researchers to find out what annoys us, why we get annoyed and what's happening in our brains when our irritation rises.

Along the way, they pulled together diverse strands of research into what just might become a new field of scientific inquiry.

Let's start with a fun question. I'm sure that as you were writing this book, you heard from a million people about their annoyances. Do you have any favorites?

I like the ones that are like, "Whaaa? Why does that annoy you?" One that just blew me away was when we were doing a talk show and someone called in and said it really annoyed her when people picked lint off her clothes. And I thought, "Picked lint off?" I couldn't even remember anybody doing that to me.

But it actually opened a whole interesting area of inquiry. Because my first question was, "Well, who does this? Does that happen to you a lot?" I asked her that, and she said, "Well, you know, it's usually my family." "Mmm, OK, so why?" "Well, they were always very fastidious about dressing and going out ironed and creased and combed. And I feel like I never quite measured up." And I thought, isn't that interesting? Because it really does prove one of the things we talk about in the book, which is that what annoys you is more revealing about you than about the thing that's annoying you.

Another one, which I didn't even quite understand, was when somebody said, "It really bothers me when they don't count change into my palm. You know, if I give somebody a $10, and get $3.75 back, they just hand the whole thing to me instead of going one, two, three." And I thought, "What?" I never did get to the bottom of that one.

But there's just no way of predicting this. That's why it was hard to come up with these universal laws about what makes something annoying.

So is there a "universal theory of annoyingness?"

This is where my academic training either helps or gets in the way, depending on how you want to think about it. I think if I had handed this book in as a graduate thesis, I wouldn't have graduated. But this is not an academic treatise. This was sort of an interesting inquiry into an area that hadn't really been looked at.

I don't know how you put the smell of a skunk, the sound of fingernails on a blackboard, someone clipping his nails and overhearing a cell phone conversation into one definition of what is annoying — but each one of those things is annoying in itself.

So with that caveat I'll say that one of the things that seems to be a factor in [annoying people] is that it has to be unpleasant. But I think the key part is that it's not deadly. We define annoyances as being essentially trivial. They may be unpleasant, but they're not harmful, in general. I suppose if a skunk sprayed you in the eyeball that would be bad, but mainly [it's] just, "Ugh, I don't like this very much."

The other thing is, it's something unpredictable. If you can get away from it, it's not annoying. We talk about cell phone conversations being annoying. But they're not annoying if somebody's just walking past you in the street. So it has to have this quality of "you're trapped and can't get away."

And then the third "u" is uncertain duration. There's this element of, if you know that the delay on a particular airline flight is going to be 10 minutes, then pfff …10 minutes. You look at your watch, you might get a little impatient, but you're not necessarily going to get annoyed because you know that in 10 minutes you're going to take off. But if the delay is undetermined, and it's 10 minutes and nothing's happened, and it's 20 minutes and nothing's happened, then the irritation begins to grow.

Things can be annoying without having that quality. I mean, clipping your nails — even the first clip is annoying, you don't have to wait for the next one, if it's something that bugs you. But that extra quality of "when is this going to end" seems to be important.

Is the annoyance you're feeling a separate emotion from, say, mild anger? Had the psychologists and other researchers you talked to thought of it that way before?

No, I don't think that most of the psychologists we talked to [had]. A lot of psychologists said, "It's mild anger, it's frustration." So we were at a bit of a loss to convince any of these people, who've put their research into the anger category or put their research into the frustration category, to say, "Well, we think annoyance is something slightly different than that."

And we still do. I think there's an argument that if you do your Venn diagram, there are certainly overlaps with a lot of these other emotional states. But I think there's a spot that annoying sits in that is unique to annoyance.

But again, this is the difference between an academic study, which we didn't do, and a journalistic inquiry, which we did do. In the best of worlds, we're hoping that somebody finds this interesting enough to carry forward.

I know that Linda Bartoshuk, at the University of Florida, has expressed interest. She's very big on studying hedonic behaviors, so she's trying to come up with [different] scales for measuring things like taste. She's trying to work on ways of making them comparable, so that, in other words, if I say my annoyingness right now is a six, and you say your annoyingness is a six, on a scale of one to 10, how do we know how your six and my six compare to one another? I think that's an interesting psychological question.

You talk in the book about how annoyances are not that important, but may be evolutionary remnants of something important. Can you talk about that?

I think they're definitely remnants of things that, when we were a different organism or had different capabilities, were potentially life-threatening. Bad smells were indicative of low oxygen. Bad sounds, screams and things like that — it turns out that fingernails on a blackboard have a similar acoustic signature. I think in general these are a civilized version of the simple withdrawal reflex. The response to the stimulus is "get me out of here," basically. But again because the stimulus isn't that severe anymore, either because we've socialized it or we've made it physically less dangerous, all we're left with is the sort of residual "this doesn't feel right and I don't want to be here."

Tell us a little bit about your psychology background and your path to journalism.

I got interested in psychology when I was a freshman in college because I was visiting Stanford University — a friend of mine was in a dorm there — and the dorm resident was a guy named Bill Dement. He is the father of modern sleep research. He had set up a sleep lab in the basement of the dorm, and the dorm students were allowed to run subjects down there. I stayed up this one night and watched as the paper went through the machine and the squiggly lines played out, and it just amazed me that you could see from these lines that didn't mean anything to me at the time that somebody was dreaming.

I thought, "This is a window into people's brains, this is so interesting. Can we really look inside at how people's brains work?" And that's what got me started. I've always been interested in how the brain works. I became a little disillusioned about the fact that the connection between the squiggles on the page and dreaming is still a little vague and a lot of the answers aren't there. But the questions are still fascinating.

So these questions about brain and behavior have always been in my mind. And so I went through undergraduate, and then graduate school and wound up working with this sleep researcher who I admired from my undergraduate days.

I was going along being a sleep researcher in the psychology department at UC–Santa Cruz. And then I thought, "Can I do this for the rest of my life? Can I be a psychologist?" I liked teaching, but I wasn't really crazy about the research part of it — I sort of lost interest in projects before they came to fruition.

I saw an ad in Science magazine for this program to take scientists and put them into media sites, and I did it, I did a summer at a television station, and I was hooked.

Really, I think journalism — the way I do it anyway — satisfies my teaching craving, because I'm trying to explain things to people. I think science journalists have a slightly different role than sports writers do because a sports writer is not going to explain to you what an RBI is, or an earned run average. You either know because you're reading the sports page, or you don't. But I can't make those assumptions in science. I have to explain to people what a bond is between two chemicals. I have to tell them more.

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