Sally’s very loud — and very fake — public orgasm in the film “When Harry Met Sally” was her emphatic way of proving that Harry has no clue if the revolving door of women he sleeps with are satisfied or not.

Although the jury is still out on one-night stands, a new study of relationships by Canadian psychologists has found that men and women are equally good at picking up on their partners’ sexual satisfaction. If you’re in a committed partnership, your lover already knows how much you’re enjoying yourself in bed — so no need to start using Sally-esque theatrics to get your point across, in other words.

But, for better or worse, the study results also mean that you probably can’t hide dissatisfaction with your sex life well, either.

The researchers surveyed members of 84 heterosexual married or cohabiting Canadian couples on their own levels of sexual satisfaction, as well as what they perceived their partners’ to be. They also looked at relationship happiness, sexual communication and general emotion-recognition ability. First, ratings of sexual satisfaction from each partner were compared with the other, to see how couples stacked up.

“On average, both men and women did well,” said Erin Fallis, study author and psychology graduate student of the University of Waterloo in Ontario. “They had, overall, accurate and unbiased perceptions of their partners’ sexual satisfaction.”

Those who rated themselves as having good sexual communication were, predictably, better at judging their lovers’ pleasure levels. But even for those whose verbal communication was lacking, some made up for it by being naturally adept at reading human emotion. Emotion recognition ability was tested by showing subjects photos of people’s eyes and having them guess which emotion the look was conveying.

Also, judging a partner’s pleasure correctly may arise from natural compatibility rather than relationship longevity, since accuracy was independent of how long the couple had been together.

The study was published online Thursday in the journal Archives of Sexual Behavior.

Some studies in the past had hinted that men overestimate how much satisfaction their female partners get from sex. One survey from 1992, by pioneering sociologist Edward O. Laumann of the University of Chicago, found that 43.5 percent of men reported that their partners always had an orgasm, but only 28.6 percent of women self-reported having orgasms.

A more recent study published in 2010 found a similar result: 85 percent of men said their partners had an orgasm during their last sexual encounter, but only 64 percent of women said the same.

But Fallis noted that these were studies of individuals, not couples; plus, there’s arguably more to sexual satisfaction than reaching climax.

“I would discourage against looking at orgasm as a comprehensive measure of sexual satisfaction,” she said.

But Laumann said their subject recruitment methods are flawed. While he performed mostly in-home interviews for his 1992 sex survey, Fallis and her colleagues had couples come into the lab together to answer questions for the three-hour-long study — which probably selected out any subjects with troubled relationships.

“A couple who don’t really care much for each other anymore — are they going to rush in to do this kind of survey?” he asked. “It imposes a lot of requirements on the couple to be cooperative.”

The couples overall rated themselves quite content with their relationships, and Fallis isn’t sure the results would hold for couples in distress.

“It’s a happy message, but it’s not necessarily a valid message,” Laumann said. The researchers “have a lot of information, but they didn’t pay as much attention to who they got it from.”

Psychologist James McNulty of Florida State University, who was not involved in the study, said he wondered what kind of impact accurate perceptions of a partner’s sexual satisfaction would have on the relationship.

In a healthy pairing, perhaps noticing a partner’s waning enthusiasm could push for a much-needed update of a couple’s sexual script — the series of actions and routines that a couple develops when it comes to sex. A sexual script can include factors such as time of day, extent of foreplay, weekends vs. weekdays and location in the house. A shot of novelty can boost levels of pleasure for all parties involved, which can ultimately prove positive for a relationship.

“Sexual satisfaction is the strongest predictor of men’s relationship stability — whether they break up or stay together,” Fallis said, citing an extensive review paper of studies on married couples. “It’s the second strongest for women after relationship satisfaction.”

Clinical psychologist Gregory Kuhlman of Brooklyn College, also not involved with the study, said the results should encourage individuals to speak freely about sexual frustrations or unmet needs, since partners probably already know if they are feeling unfulfilled.

But how to bring it up without offending or upsetting someone is another hurdle. Recognizing that a happy partner is happy can be great, but the opposite — discerning unhappiness — can be threatening and anxiety-fueling, McNulty said.

“The standard advice about discussing sex is: Don’t do it during sex,” Kuhlman said. “As with any potentially sensitive topic, pick a time when you’re both well-rested, undistracted, etc.”

Kim is a freelance science journalist based in Philadelphia.