For example, in 2017, the Department of Labor filed a lawsuit and investigation against Google. Their regional director Janette Wipper told the Guardian, “discrimination against women in Google is quite extreme, even in this industry.” The suit claimed that Google refused to disclose data on employee salary history, as required by equal opportunity laws.

Which brings us to the wage gap. Rather than a deliberate, methodical attempt to sabotage women’s earnings, often the wage gap takes on more subtle, but no less detrimental forms. For example, women are viewed as less likable when they negotiate. They’re also less likely than men to get what they want when they ask for a raise, according to Harvard Business Review.

“By keeping compensation secret, we might obscure structural inequalities and enable inequalities to persist,” said Morela Hernandez, a researcher and Associate Professor of Business Administration at the Darden School of Business at the University of Virginia. In the big picture, it’s easy to see how these biases might contribute to a wage gap, but it’s harder to prove wage discrimination on an individual level. Employers can hide “structural inequalities” (even from themselves) with a myriad explanations. When wages are transparent, it’s harder to hide.

It’s not just women. Pay secrecy reinforces racial biases as well, and the pay gap is wider for black and Hispanic men and women, according to a recent report from the Bureau of Labor Statistics. In a study with her colleague Derek R. Avery of the Wake Forest University School of Business, Dr. Hernandez found that when black job applicants negotiated their starting salaries, evaluators viewed them as more pushy than white job applicants who also negotiated. Evaluators also mistakenly thought black job applicants negotiated more than white applicants, even when they negotiated the same amount. Worse still, the black job applicants received lower starting salaries as a result of this.

Dr. Hernandez said that because evaluators expected black job seekers to ask for less, they perceived the black applicants as pushy when they negotiated and penalized them accordingly. In the real world, employers probably aren’t even aware of this dynamic; that’s how unconscious biases work. When numbers are out in the open, however, it’s easier to see potential blind spots.