But Darley said the apparent escalating brutality of the alleged attack may have had less to do with its sexual nature and more to do with the isolated location.
Marin Trujillo, a spokesperson for West Contra Costra Unified School District, said the attack occurred in a locked area not easily accessible from the enclosed gym where the homecoming dance was held and where security, which consisted of four police officers and numerous staff chaperones, were concentrated.
In fact, Darley said the seeds of behavior that could become unacceptable are evident when, for example, men catcall or whistle at people on the street, where social barriers prevent escalation. Military attacks on villages are another example where events can escalate beyond what is expected.
Other elements that may prevent bystanders from taking action could include fear of disciplinary action, particularly when alcohol is involved, as well as fear of seeming less masculine, Bossong said.
Richmond High School still is struggling to make sense of an event officials say has never happened previously and that they were unprepared for.
"This was a horrible, heinous crime that happened to one of our students," said Trujillo. "We see it not as a Richmond High School incident but as a national incident."
According to data from the Pennsylvania Coalition Against Rape, one in four girls and one in six boys will be sexually assaulted by age 18 and 23 percent of sexual offenders are under age 18.
Beginning with Richmond High School, Trujillo said the entire school district plans to improve programs on safe teen dating and training around sexual assault to create a "joint plan of action and a joint sense of understanding."