PHILADELPHIA - She's bright and creative, and 11-year-old Caroline Robb has autism, which is challenging when she's trying to fit in with other pre-teens in middle school.

"I used to run around by myself on the playground," she said. "I didn't really get to talk to a lot of people. I kind of sat out a lot."

She uses "feeling" words to describe her situation, and that's what differentiates her from boys with autism. They usually only use concrete words.

"Girls with autism will tend to kind of hover near social groups out on the playground, and I think that kind of behavior, the hovering near, can make it complicated for people when they're looking for autism," said Julia Parish-Morris, a scientist at the Center for Autism Research at Children's Hospital of Philadelphia.

Even Caroline's parents, who had her diagnosed at four, first noticed behavioral, rather than language, differences.

"It definitely was not language that took us there," said Elizabeth Robb, Caroline's mom. "It was behaviors, body movements and learning things."

"When you separate out the kids with autism into boys and girls, the girls with autism actually talked a lot more like the typical kids than the boys," Parish-Morris continued.

But here's what to listen for in boys and girls: fewer emotional phrases like "I feel" or "she thinks" and more concrete words, and kids who are laser-focused on only one subject.

"It's not universal to all girls, neither is it exclusionary of all boys, but to really pay attention to the other more subtle things that might be showing up in girls and young children that have autism," said Parish-Morris.

More research needs to be done to determine exactly why boys are diagnosed so much more often than girls, but experts think linguistics hold major clues. Parish-Morris said, ideally, she'd like to see society become inclusive of people with autism, no matter their language style.