'It's like a children's story," says Morna Pearson as she makes her way up the steep metal stairs of the Traverse Theatre's Leith rehearsal room after observing through a window as a group of actors throw themselves into a dance routine, "but with dirty bits."

Pearson is talking about her new play, The Artist Man and the Mother Woman, which opens at the Traverse next week, and it's the most direct she's likely to be on the subject. Such reticence is peculiarly at odds with Pearson's dramatic voice, if her 2006 debut, Distracted, is anything to go by. Set in a Morayshire caravan park occupied by dysfunctional transients, Distracted served up a wild and vivid form of Doric-accented surrealism which promised great things from Pearson.

That short play went on to win the prestigious Meyer-Whitworth new playwriting award in 2007, which meant Pearson followed in the footsteps of David Harrower, Henry Adam and Conor McPherson. The attention the then 27-year-old from Elgin received from major theatre companies, might have been expected to produce a steady stream of works to take the world by storm. But after five years The Artist Man and the Mother Woman is Pearson's first full-length main stage play.

It's not that there haven't been other sightings of the young writer. By the time she won that award, Pearson had already seen a new short play, Elf Analysis, performed as part of the Oran Mor-based A Play, A Pie and A Pint season. In 2011, an adaptation of a piece by South American writer Rodolofo Santana, which translated as The Company Will Overlook A Moment of Madness, also appeared at Oran Mor in a season co-produced with the National Theatre of Scotland. The same year, Skin: Or How To Disappear, was one of the most accomplished pieces in a compendium of shorts presented by the women's writing company Agent 160 last year. As well as two radio plays, Macbeth's MacPets and Side Effects, there were contributions to Welcome To the Hotel Caledonia, the Traverse's multiple-authored election night entertainment.

While these were all tantalising glimpses into Pearson's fantastical mind, one wanted more. If The Artist Man and the Mother Woman proves as captivating as these, the first question that needs to be asked is: what kept her so long? As it turns out, Pearson has been far from idle. It's just the rest of the world, wasn't quite ready for her.

"It's gone quickly," reflects Pearson in slightly dreamy tones. "I've done something pretty much every year, but I've been down a lot of dead ends as well with commissions that never came to anything. If I had other skills I would've maybe have stopped writing, because when you get three commissions rejected in a row, it kind of makes you think. I've definitely learnt from that not to be commissioned on one sentence, but to write a first draft. What might be a good idea might only end up being a 10-minute play, so I wouldn't say yes to anything now unless I was confident I knew what the deal was."

While she understandably lost confidence after such setbacks, Pearson maintains a quiet determination when she says of the rejected plays: "They're not in the bin. They've just been put aside for a while."

Pearson's new play takes its title from a line in George Bernard Shaw's Man and Superman: "Of all human struggles there is none so treacherous and remorseless as the struggle between the artist man and the mother woman." Pearson uses this as a springboard to see what happens when a mollycoddled art teacher attempts to extract himself from the maternal bosom after discovering he works in one of the top 10 sexiest professions.

"I always start with a character suggesting things in my head," Pearson said, "and I had this character who'd led a sheltered life, but wanted to get into the dating scene. Then I quickly realised his mother was very important to his life so I started to focus on their relationship."

This hits on a notion that most men with artistic sensibilities have been indulged by their mothers from an early age.

"Boys are definitely treated differently," Pearson observes, "and I think if my character here had been a woman she definitely wouldn't still be living at home. But most of the characters I come up with are a bit unwise."

An early draft of The Artist Man and the Mother Woman was one of the plays originally commissioned by another company, who'd passed on taking it to full production. It was only when the Traverse's incoming artistic director Orla O'Loughlin arrived at the theatre that things began to move forward.

"She'd heard of its existence and asked to read it," says Pearson, "and then she thought it would be good to have a reading of it in April. Part of that was about getting my confidence back, but I had enough distance from it to go back to it. A few weeks later the Traverse commissioned me, and I redrafted and redrafted it, so it's quite a different play now to how it was originally – even though it's gone back more to how it was in the original draft."

Whatever happens with The Artist Man and the Mother Woman, it's unlikely to be another five years before a new play by Pearson appears. Already ongoing is Ailie and the Alien, a commission for the National Theatre's 2013 NT Connections series of plays performed by youth theatres. As for her current play, while ostensibly a comedy, Pearson admits there is a dark thread running throughout.

"Some of the subject matter could be taken further," she admits, "but you don't want to alienate an audience, so I hope we've got the balance right."

The Artist Man and the Mother Woman, Traverse Theatre, Edinburgh, October 30-November 17. Visit www.traverse.co.uk.