Nearly half of sixth-grade urban middle school students reported being harassed by bullies at least once within the previous two weeks, a new study finds.

Insults such as name-calling and physical aggression, such as kicking and shoving, were the most common forms of harassment reported by the students.

"Students were bothered by all types of harassment incidents they personally experienced -- for example, being the target of insults, physical aggression or rumors -- but they were more concerned and felt sorrier for peers who encountered verbal rather than physical forms of hostility," study lead author Adrienne Nishina, a postdoctoral fellow at the University of California, Los Angeles' department of education, said in a prepared statement.

"These findings are important because they show that many more kids are affected by bullying both through their own personal experiences and by what they see happening to their classmates than previously estimated," Nishina added.

The study appears in the March/April issue of the journal Child Development.

Nishina and co-author Jaana Juvonen also found that students who said they'd been picked on expressed increased feelings of humiliation and anger. Students who saw others being picked on also had increased anxiety and dislike for school, the study found. According to the researchers, witnessing other students being bullied is linked to negative attitudes about school, lack of engagement in class, and fewer positive school experiences.

Children who were victims of harassment but also saw others being picked on were less likely to feel humiliated or angry than those who felt they were alone in being victims, the UCLA study found.

"The findings suggest that educators and other professionals should target violence intervention efforts to all students, not just those who are most victimized by their schoolmates, and all forms of bullying, not just physical aggression and certain forms of verbal harassment," Nishina said.