The 24-year-old star is so wary about being caught on camera doing something embarrassing that she acts differently to how she would if there was no one following her.
She revealed: "It's weird in Los Angeles - [paparazzi are] hiding out everywhere. The hardest thing is that it makes me act like an a**hole because I now have this weird level of paranoia that I never had before.
"It feels like having a private investigator on you or something. You find yourself walking around holding your head up like you're looking in the mirror - and your friends are wondering what's wrong with you.
"Then I feel like a jerk because half the time there's nobody there ... still, I really don't want to be caught with a burger all over my face."
Emma, who is dating her 'Amazing Spider-Man' co-star Andrew Garfield, always wanted to be an actress and was so determined to reach her goal that she once told her mother Krista she would "die" if not given the chance to act.
She added to the UK edition of Glamour magazine: "My parents knew that there was something a little off about me. So it made sense when I asked, aged 11, if I could take acting classes.
"Apparently I said to my mum, 'If I can't act, I'll die.' And then she knew - she knew that only an actress would say something like that."
Irish Examiner live news app for smartphones lets you quickly access breaking news, sport, business, entertainment and weather.
Irish Examiner ePaper app gives you the entire newspaper delivered to your phone or tablet for as little as 55c a day.
The grandmother of a toddler with Down's syndrome has been waiting a year for a response from the Taoiseach and three government ministers to correspondence about disability cuts referred to them on her behalf by the troika.