Despite Filson's own experience with rude remarks, it didn't prepare her for the stories she heard that day.
There were accounts of groping, sexual comments, and up-skirt photographs occurring at conventions nationwide. "I wasn't expecting how many women - and men - would tell us things that happened to them."
So, Filson and fellow activists Rochelle Keyhan and Anna Kegler of Philadelphia launched Geeks for CONsent, a national movement to prevent that kind of verbal and physical abuse.
They've been developing antiharassment policies, training volunteers, counseling victims, and gathering signatures to petition for stronger protections - but they've also discovered that effecting actual change can be an uphill struggle.
They drew 2,500 supporters for an online petition to improve policies and practices at Comic-Con International in San Diego, but received no official response (and unofficial discouragement, in the form of comments to the press suggesting that highlighting harassment would only exacerbate it).
Wizard World, which returns to the Convention Center this weekend, has ignored their queries, Keyhan said. A Wizard World spokesman said harassment isn't an issue at the event, and that sufficient policies - which call for the removal of anyone who exhibits threatening behavior - are in place.
But seamstress Nicole Jacobs, of Reston, Va., who often goes to conventions and makes her living sewing costumes for other fans, said harassment is rampant at such events. At AwesomeCon in Washington, D.C., a man asked to take a photo with her and her friend. Then, she said, he grabbed their breasts and urged his friend to snap the picture before they could wriggle free.
"It was infuriating. I felt disgusting - the fact that he would not only grab me like that, but that he would laugh and think it hilarious while we were clearly fighting," she said.
For Jacobs and other fans of comics, video games and movies, conventions are a chance to spend a day dressed as their favorite characters - who, like their male counterparts, often wear skintight outfits. But harassers, she said, question a woman's "validity as a person and as a real nerd."
Kimberly Fairchild, a Manhattan College psychology professor who has studied street harassment, said that's not surprising.
She views street harassment - such as catcalling as a woman walks by, or intimidating her as she sits alone on a train - as an assertion of male power over a traditionally male-dominated space; the same goes for harassment at comic cons.
Comic-book culture is born mostly among male fans and mostly online, said Dustin Kidd, a Temple University sociologist and author of Pop Culture Freaks: Identity, Mass Media, and Society. "They tend to think of it as their culture," he said. "I find they're often quite resentful of feminist critiques. . . . Perhaps some of that hostility that gets built up online plays out at conventions."
Kidd said there are many examples of misogyny in nerd culture - see the "fake geek girl" meme that circulated on the Internet a few years back or, more generally, the proportion of female characters whose primary role is either victim or love interest. But a bigger problem is mainstream pop culture, in which women are likewise underrepresented (they are just 40 percent of TV characters) and hypersexualized.
Plus, there's a double standard: A man showing off his muscles in superhero garb might appear strong, he said, but a woman in costume is seen as the recipient of male fantasies.
"Women in those kinds of outfits get read by men as displaying themselves for sexual reasons, as opposed to representing a superhero," Kidd said.
Whatever the causes, Fairchild said the consequences of harassment can be serious.
"It makes women more likely to self-objectify. They start to think of themselves as body parts, objects, not full intelligent human beings. . . . Objectification, in turn, has been linked to depression and anxiety."
She said that, while changing harassers' behavior is a long-term goal, creating a safe space for women to report complaints, and have them taken seriously, could make a difference right away.
"Most women react to harassment very passively. They try to ignore it and pretend it didn't happen," she said. But having a chance to report it, and receiving acknowledgment that the behavior was inappropriate, can mitigate some of the negative emotional consequences.
To that end, Geeks for CONsent has developed an antiharassment training manual for conventions to use, and a set of recommended policies. At AwesomeCon this spring, they provided training materials and staffed a booth where people could talk about these issues (though, as Jacobs' experience showed, incidents can happen even when extra precautions are taken). They're also helping out at J1Con, an anime convention coming to Philadelphia in September.
They're lobbying all conventions to meet the same baseline: clearly written policies on harassment, signage reiterating those policies, and training for volunteers and staff to implement them.
When organizers follow those steps, Keyhan said, "People say they feel very safe in those conventions, because it's already in the air: Everyone knows what is right and wrong."
Since Wizard World didn't respond, Keyhan said, she'll be there in an unofficial capacity to spread the word.
"We're teaching people how to be good human beings," she said. "It's common sense - but maybe not, if you're sort of socially awkward or were raised feeling entitled. Maybe no one bothered having that conversation with them."