That’s the view of the vast majority of male employees when it comes to workplace discrimination faced by women, according to a new PayScale survey—and it points up a huge challenge to overcoming the problem: You can’t fix something that you don’t see.

The PayScale survey, conducted online over the past couple of months with about 140,000 people from a broad range of industries, found that 67% of men believe that in most workplaces “men and women have equal opportunities.” Yet only 38% of women say that’s the case.

For those in jobs related to technology—a field that has found itself under heavy scrutiny for the way women are treated—the gap is even larger: 66% of men in tech positions say there is equal opportunity for all in most workplaces, while just 30% of women in tech do.

The findings jibe with studies done by others, including this 2015 study by the Pew Research Center.

“There’s clearly a difference in perception,” says Aubrey Bach, a senior manager at PayScale, a Seattle-based provider of compensation data, who will present the survey results during a panel on Sunday at the South by Southwest Interactive Festival. “Men don’t think inequity is an issue.”

The reality, however, is that it is.

Overall, women continue to earn 15% to 20% less than men—a disparity that grows the longer that women remain working outside the home. In the U.S. and Canada, Mercer has found, women account for a mere 22% of corporate executives, 30% of senior managers, and 38% of managers (even though they make up nearly half the American labor force). And research by Michelle Budig, a sociologist at the University of Massachusetts at Amherst, shows that when families have children, fathers get a wage bonus; mothers suffer a wage penalty.

Interestingly, the PayScale survey found that both men and women have relatively favorable impressions of how women are treated inside their own companies. Seventy-five percent of male employees in general and 80% of men in tech jobs say there is equal opportunity for all at their workplace. By comparison, 51% of women and 44% of women in tech positions say that’s so.

Matt Wallaert, a behavioral scientist who will take part in the SxSW panel, suggests that people often have a hard time admitting that their own employers aren’t fair to everyone because it can make them uncomfortable. “It’s psychological protection,” he says. In any event, the gulf between what men and women feel is happening where they themselves work is every bit as enormous as what they think is true of the wider world.

That so much empirical information is out there—and yet so many men fail to recognize what their female colleagues are up against, especially in tech—frustrates Wallaert, who is the co-founder of GetRaised.com, a free service that helps women obtain higher pay.

“It’s those in the tech industry, which thinks of itself as full of logical and data-driven engineers, who are most likely to say sexism isn’t a problem in their workplace,” he says. “That’s just amazing. There is a real need for men to step up to the plate.”

Perhaps part of the reason that men are largely blind to gender bias in the workplace is that, all in all, it’s not nearly as blatant as it was in the 1950s and ’60s, when the ranks of women entering the labor force began to swell. Back then, it wasn’t uncommon for major employers to focus on a woman’s appearance, not her aptitude.

“This winsome lass is Carol Goff, a clerk-typist in shipping,” General Electric’s distribution transformer department in Oakland, Calif., announced in the “Who’s New” section of its internal newsletter in late 1961. “Another pretty lil’ gal, Joyce A. Tate, is our new mail girl.” When one of GE’s few female engineers had visited a company factory in Massachusetts in the mid-1950s to check on some production parts, she’d gotten the same treatment. “Not even a visitor from Mars could have attracted more attention than Betty Lou Bailey,” a GE publication reported. “Not that the visitor had any of the characteristics of a Martian—in fact, with her blue-eyed, blonde-haired attractiveness she would have been an eye-catcher anywhere.”

But just because sexism is now simmering more beneath the surface doesn’t mean it isn’t there.

“Companies play hot potato with the issue,” says Liz Morgan, who is in charge of recruiting Bay Area engineering leaders at LinkedIn (LNKD). “They usually look to HR and recruiting to fix the problem by increasing the talent pipeline with more female candidates and conducting unconscious-bias training. It’s a good start, but more needs to be done.”

Morgan, who will join Sunday’s panel, recommends that companies take a number of specific steps, including more rigorously evaluating and making transparent hiring, compensation, turnover, and retention data—“and holding management accountable” when there are inconsistencies between men and women. At least a few companies, such as Salesforce (CRM) and Pinterest, are moving in this direction.

Morgan also calls on companies to do what the NFL — not normally regarded as a paragon of progressive attitudes toward women — is doing: instituting “the Rooney Rule,” which would require that they interview women (and others who would bring more diversity to the organization) for executive positions. In addition, she says, they must build a deeper internal bench of potential women leaders and that it’s important for companies to establish equal standards and expectations for men and women on policies such as flex time, and paternity and maternity leave.

Finally, says Morgan, corporate leaders need to work harder to foster a truly “collaborative culture.” One key to this, she says, is that companies should make sure that formal support networks designed to help women include men.

“Right now, they’re not consistently part of those conversations,” Morgan says.

Evidently, that’s helped them reach a faulty conclusion: that gender discrimination is a thing of the past when, the truth is, there’s a long, long way to go.

Rick Wartzman is senior advisor to the Drucker Institute at Claremont Graduate University. The author or editor of five books, he is currently writing a narrative history of how the social contract between employer and employee in America has changed since the end of World War II.