So last night’s suave but subtle move failed—again—to score you a number. Well, good news (sort of): She may not have even known you were interested.

In a new University of Kansas study, 52 men and women were paired up for 10- to 12-minute chats, then asked if they felt they’d been flirted with. While over 80% of the time subjects knew when they weren’t being hit on, recognizing when they were proved much tougher, with guys realizing it only 36% of the time—and women just 18%.

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“It’s pretty easy for others to see when you’re not interested,” says U. of K.’s Jeffrey Hall, Ph.D. “The hard part is showing them when you are, without seeming overly aggressive or foolish.”

Direct is better, according to Hall. Straight questions like, “Are you in a relationship?” or “Can I see you again?” are sure to get the message across, he says, “but try to fit them naturally into conversation.”

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