When 51-year-old comedian Paula Poundstone performs, there are only two things that matter: herself and the audience. She never performs with other comedians, and she doesn’t want anything or anyone coming between her comedy and the crowd.

Poundstone, famous for her interactions with the audience during her shows, will be performing at the Capitol Theatre at 7:30 p.m. Friday.

She has been featured on “The Tonight Show” and “The Rosie O’Donnell Show.” She currently is a panelist on “Wait Wait… Don’t Tell Me!,” a weekly quiz show on National Public Radio.

She said she never works with other comedians because she likes to keep the crowds to herself. This allows her to slow everything down and perform one long set.

“I’m really selfish about the way I work,” she said. “I do two hours, and it’s just me. My crowds are so much fun that, honestly, I don’t want to share them. It doesn’t make any sense to me.”

Poundstone started her stand-up comedy career in 1979, when she would perform at open mic nights in Boston. Slowly, she and her comedian friends began to become more prominent.

“When I started out, I was among a group of people starting out at the same time,” she said. “I refer to them as my graduating class. I took a Greyhound bus around the country to see what (comedy) clubs were like in different places.”

Besides comedy, Poundstone has devoted much of her time to parenting several children and pets.

However, in 2001, Poundstone was arrested and charged with driving under the influence and child endangerment. In 2002, the comedian pleaded guilty to felony child endangerment, according to CNN.

She said being a mother has not only left an impact on her personal life, but also her performances. When she was younger, her act would include a joke about how much she despised crying babies on airplanes. Now, she said her feelings could not be more different.

“Now, I love babies,” she said. “If there’s somebody that has a baby I’m thrilled when they sit beside me on the airplane.”

Another one of Poundstone’s passions is literature. She is the national spokesperson for ALTAFF, the Association of Library Trustees, Advocates, Friends and Foundations, and she is passionate about the superiority of the physical book over electronic devices.

“There’s something about the cover of the book, the weight of the book, the feel of the book and the pages of the book that enhance the experience of reading,” she said. “I look around the airplane, and people have books and magazines. I don’t think it’s going to disappear like dinosaurs from the face of the Earth. It’s comforting. I don’t see how you could be comforted by a Nook.”

When Poundstone wrote her book “There’s Nothing in This Book That I Meant to Say” in 2007, she wrote it entirely by hand.

“My feeling was there was something about the drag on the pen that I really liked in the writing process,” she said.

In terms of her performances, Poundstone said the keys to a good stand-up routine are “rhythm and connection.”

“There is a magic to a crowd that has come out to laugh for the night,” she said. “I’ve watched guys say stuff that — when you thought about what they said — was unbelievably not-funny. Yet I laughed and the crowd laughed when we heard them say it.”

Even though she thinks she’s figured it all out, she said the real key to consistently great performances can never be specified.

“If I absolutely knew how to do a stellar show, then I would be too goddamn busy to even have this conversation,” she said. “The truth is, I don’t really know. It’s a mixture of so many elements, and most of them are ethereal and magical, and you can’t really put your finger on them.”

She still believes in a few superstitions.

“If I had a really good show, I would try to wear the same shirt that I wore that night (for another show),” she said. “I was certain that it was somehow wrapped up in what shirt I wore. I’m not convinced, even to this day, that it’s not.”

Because of her act’s reliance on audience participation, each of Poundstone’s shows look to be different than anything she has done before. She said that while she prefers this ever-changing style, it is not impossible for other comics to merely recycle old material. It just isn’t the way she likes to work.

“I have friends that have done the exact same act, without a word differently, 20 or 30 years as well,” she said. “They do it brilliantly and great.”

Poundstone said she doesn’t change things up merely to entertain the audience. Many of her reasons are purely psychological.

“By the end of the weekend, I’m sick of the sound of my own voice,” she said. “If I were saying the exact same words, I think I would probably eventually blow my brains out.”