Overt prejudice against women is hard to miss, but decades of research suggests that subtle sexism can be just as damaging — but often goes unnoticed.

Peter Glick of Lawrence University in Appleton, Wisconsin, and Susan Fiske of Princeton University have spent 20 years studying the subject. In 1996, they published a study in the Journal of Personality and Social Psychology that introduced a theory they called ambivalent sexism. The idea behind it is this: sexism is “multidimensional” and more nuanced than many people realize. And it comes in two forms: hostile and benevolent.

Hostile sexism describes behavior that overtly threatens, intimidates or abuses women. Benevolent sexism describes positive attitudes and actions that men take toward women that are based, deep-down, in feelings of superiority and dominance.

“In short, hostile sexism represents the ideological stick, and benevolent sexism represents the carrot that men use to reinforce the gender status quo,” Glick wrote in 2007.

Together, Fiske and Glick developed the Ambivalent Sexism Inventory, a questionnaire that explores people’s tendencies toward hostile and benevolent sexism. These 22 questions aren’t designed to diagnose a respondent as sexist or not, and the results aren’t nationally representative. But the researchers say the quiz can shed light onto whether an individual harbors attitudes associated with sexism.