How important is that first kiss? Very, according to a new study.

Oxford University researchers found that — as they expected — women are more likely than men to change their opinion of others after they kiss them.

“Mate choice and courtship in humans is complex,” researcher Robin Dunbar said in a press release. “It involves a series of periods of assessments where people ask themselves, ‘Shall I carry on deeper into this relationship?’ Initial attraction may include facial, body and social cues. Then assessments become more and more intimate as we go deeper into the courtship stages, and this is where kissing comes in.”

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The researchers surveyed over 900 adults, asking questions such as, “How important do you think kissing is at the very initial stages of a relationship?”

They found several differences between men and women: women rated kissing as more important in long-term relationships than men did, and more important at times other than when having sex. In fact, women rated kissing as all-around more important in relationships than men did.

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One thing that crossed gender lines: how much couples smooch is a sign of how happy they are together.

The researchers weren’t surprised that kissing is used to assess potential partners or to keep relationships thriving, but they were surprised that results of their survey suggested that kissing is not linked to increasing sexual arousal.

The findings were published in the journals Human Nature and Archives of Sexual Behavior.