AceShowbiz - Shia LaBeouf is intimidated working with professionally trained actors because he's convinced their studies enable them to be better improvisers.

The "Disturbia" star found fame as a young actor on Disney Channel series "Even Stevens", and admits everything he knows about working on set he learned on the job.

However, his lack of classical training has left him with feelings of insecurity, which he began experiencing from the start of his career in the limelight.

Recalling his behaviour on set as a kid in Variety's Actors on Actors series with fellow child star Kristen Stewart, he said, "I used to walk around with a pen and a pad, almost litigious, like: 'Hey, what's your name? Oh, cool.' Then I'd write it in a little notepad..."

"I wanted to seem studious, because I didn't go to (acting) school and I didn't learn how to do this acting thing."

As a result, LaBeouf never feels fully comfortable around people like Stewart's "Seberg" co-star Anthony Mackie, who is a graduate of New York City's prestigious Juilliard School.

"If you get around a guy like Mackie, who's gone to school, he's got technique. Those people make me very scared," he said.

"I feel judged, like I'm an outsider. If my knitting needle breaks, I don't have a f**king knitting needle. Guys like that, their knitting needle breaks, and they're, like, 'Let me go in the kitchen and I'll whip something together and I'll come back and I'll knit this sock for you.' "

Bonding with LaBeouf over their shared "chip" on the shoulder, Stewart revealed how she tries to compensate for her lack of acting training, saying, "I read a lot. I'm always like, 'I didn't go to school, but...' "

The "Twilight" star was just nine years old when she began her career onscreen back in 1999, and she scored her big break alongside Jodie Foster in 2002 thriller "Panic Room".