NEW YORK - It can be a malicious rumor whispered in the hallway, a lewd photo arriving by cell phone, hands groping where they shouldn't. Added up, it's an epidemic - student-on-student sexual harassment that is pervasive in America's middle schools and high schools.

During the 2010-11 school year, 48 percent of students in grades 7-12 experienced some form of sexual harassment in person or electronically via texting, email and social media, according to a major national survey being released Monday by the American Association of University Women.

The harassers often thought they were being funny, but the consequences for their targets can be wrenching, according to the survey. Nearly a third of the victims said the harassment made them feel sick to their stomach, affected their study habits or fueled reluctance to go to school at all.

"It's reached a level where it's almost a normal part of the school day," said one of the report's co-authors, AAUW director of research Catherine Hill. "It's somewhat of a vicious cycle. The kids who are harassers often have been harassed themselves."

The survey, conducted in May and June, asked 1,002 girls and 963 boys from public and private schools nationwide whether they had experienced any of various forms of sexual harassment. These included having someone make unwelcome sexual comments about them, being called gay or lesbian in a negative way, being touched in an unwelcome sexual way, being shown sexual pictures they didn't want to see, and being the subject of unwelcome sexual rumors.

The survey quoted one ninth-grade girl as saying she was called a whore "because I have many friends that are boys." A 12th-grade boy said schoolmates circulated an image showing his face attached to an animal having sex.

In all, 56 percent of the girls and 40 percent of the boys said they had experienced at least one incident of sexual harassment during the school year.

After being harassed, half of the targeted students did nothing about it. Of the rest, some talked to parents or friends, but only 9 percent reported the incident to a teacher, guidance counselor or other adult at school, according to the survey.