In the early 1990s, the first-ever nationally representative sex survey in the United States was conducted. Researchers discovered a lot of things about American sexuality at the time, but one of the most notable was that men were hogging all the orgasms.

Men were two-and-a-half times more likely than women to say they orgasm consistently during sex, the survey found. Specifically, 75 percent of guys said they always orgasm with their partner, compared to just 29 percent of women.

The good news is that this gap seems to have narrowed a bit in the last quarter century. A 2010 national sex survey found that whereas 85 percent of men said they orgasmed the last time they had sex, 64 percent of women reported that the same. Although the orgasm gap appears to be declining, the fact that it exists at all is problematic. So why is that? Why are men still so much more likely than women to reach orgasm?

A new study published in The Journal of Sexual Medicine highlights one contributing factor: A lot of heterosexual men think their partners are orgasming more than they really are. If a guy thinks his partner is having orgasms when she isn’t, it stands to reason that he probably isn’t going to take any steps to address the issue because he doesn't even realize there’s a problem.

In this study, researchers looked at a nationally representative sample of nearly 1,700 heterosexual newlywed couples. They compared how often husbands and wives said they actually orgasm during sex to how often their partners think they orgasm. They also looked at how orgasm misperceptions were linked to participants’ sexual and relationship satisfaction.

Consistent with previous research, evidence for an orgasm gap emerged. Specifically, when you look at whether people said they had regular orgasms with their partner (defined as orgasming more than 80 percent of the time they have sex), nine in ten men agreed compared to just one in two women.

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When comparing people’s actual orgasmic experiences to their partners’ perceptions of them, it turned out that wives were highly accurate: 86 percent of women were spot-on in their estimates of how often their husbands were orgasming. Just six percent underperceived their partners’ orgasms, while eight percent overperceived them.

What about husbands? Just 58 percent were accurate at estimating their wives’ orgasm frequency. The rest were split between underestimators (17 percent) and overestimators (25 percent). Women were more satisfied with their sex lives when they orgasmed more often, when their partners accurately perceived their orgasms, and when there was more sexual communication in the relationship.

Men were also more satisfied when they accurately perceived their partners’ orgasms and when they had more frequent sexual communication. Interestingly, however, men’s sexual satisfaction was unrelated to how often they themselves were orgasming, but that’s probably because most men have orgasms most of the time anyway.

Why do so many men get it wrong when it comes to whether their partners are climaxing? Part of it may be that men are getting their ideas about what a female orgasm looks like from porn. When women orgasm in porn, they tend to be very vocal and show a lot of facial cues of pleasure—so maybe some guys are using these same criteria to infer their partners’ orgasms. This could help to explain why one in five guys underestimated their wives’ orgasms: Maybe they were expecting a performance.

The fact that women sometimes fake orgasms may be contributing to male misperception as well. Women fake orgasms for a wide range of reasons, from not wanting to hurt a partner’s feelings to showing appreciation for a partner’s efforts to just wanting sex to be over. And if they fake it with a spouse once, they might feel pressure to continue faking it, which is going to exacerbate the misperception problem, leading their husbands to believe their orgasms are more frequent than they really are.

It’s also possible that a lot of guys overperceive their partners’ orgasms because it’s an ego-defense strategy. In other words, maybe they want to feel masculine or sexually competent, so they just assume that their partners are orgasming without really checking in with them because they’re afraid to find out they might not be as good at sex as they think—or hope—they are.

Regardless of the reason(s) behind men’s orgasmic misperceptions, the data is clear in showing that men who are more attentive to their partners’ orgasms are more satisfied with their sex lives—and their partners are, too.

This tells us that if we really want to close the orgasm gap once and for all, one thing we need to work on is closing the orgasm perception gap. One of the best ways we can do this is by improving sexual communication skills. People need to feel empowered to tell each other what they want when it comes to sex, but also to ask their partners what they really want and enjoy, too.