Emily Blunt's stutter was so bad, she "could never say [her] own name".
The 36-year-old actress' speech impediment was "ingrained" in her by the age of 12 and she soon realised that "pressurised" situations caused her the most problems.
She said: "School was interesting because there were certain things I couldn't do and wanted to, like read out my poem in class. I would never want to do that. I would hate it if the teacher called on me to answer something ... I didn't love calling my friends. I could never say my own name if someone said, 'What's your name?' Because you can't substitute a word out, which is what we tend to do to find a better flow. You substitute another word that's easier, and you can't substitute your name.
"So I realised quickly as a kid, any pressurised situations were quite hard for me."
The 'A Quiet Place' star - who has daughters Hazel, five, and Violet, three, with husband John Krasinski - admitted even now her stutter can creep in when she's working, but usually only during very specific types of scene.
She explained to the new issue of Marie Claire magazine: "The only time I feel I sometimes stutter when acting is in these high-octane scenes where there's an emergency happening, where I have to say, like, 'Get in the car!' or 'Where's your bag?' or something like that.
"I was speaking to Samuel L. Jackson... He said he was shooting one of the Marvel movies and had a scene where he had to say, 'Let's get out of here!' and he couldn't say it.
"It was a scene with one of those crazy explosions going off. Instead, he said, 'We got to go!' And they said, 'Cut. Sam, the line's 'Let's get out of here.'
"And he said, 'Yeah, got it.' He had to fake that he'd forgotten it. He went to say it again and said, 'We got to go!' And he said, "You know what, I'm just going to change the line.'
"Those high-octane emotional scenes, where I'm having to demand information out of somebody, are the only times where I feel I trip up."
But Emily doesn't consider her speech impediment when looking for new roles as she knows it's something she work around if it becomes a problem.
She said: "I don't ever consider my stutter now when it comes to what roles I choose or why I want to do it. It is not something that I even think about.
"And any sort of stutter steps I might have, or things that I'll get tripped up on, or lines that could be tricky, I'll sort of just find a way around them.
"I think with experience, you discover the confidence in knowing you'll just find a way around it."