I love to hug my friends hello and good-bye, and to give and receive hugs and kisses with my partner, Simon. We hug in greeting, in thanks for doing a favor, or pretty much anytime we feel like it. Plenty of studies have looked at affection between partners and friends and the results are clear: the more, the better. Such physical touch boosts immunity, blunts depression and lowers stress levels.

But when it comes to people I don't know, it's a different story.

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In California, where I've been living for the past year, it's common to hug in greeting — even with someone you're just meeting for the first time. In New York, most people shake hands. (I must be a New Yorker at heart because even though I consider myself an affectionate person, I just don't like hugging people I don't know. Shouldn't a hug be earned?)

I'm certainly not the only one who feels this way. A new study published in the Proceedings of the National Academy of Sciences includes a "touch map" put together by Oxford University that shows significant variability in where and how people like to be touched by people they know and by people they don't. The study asked more than 1,368 people from five countries to indicate where they would be comfortable being touched.

Touching chartWhen it comes to touch, relationships matter. (Photo: PNAS)

As you can see in the chart above from the study, the closer the relationship, the more comfortable people were being touched in more areas of the body. There wasn't a huge difference in people from the different countries, although overall British people were least comfortable with touching and Finnish people the most. But there was only one place where almost all people who answered the questionnaire said they were comfortable being touched: their hands.

Overall, women are more comfortable than men being touched, which is perhaps why we see touching beyond a handshake even in business settings, as women gain more places of power in the world.

As Natalie MacNeil details in her video above, where you are can make a difference too. She was fine with people who were fans of her book hugging her at book signings, but she considers a handshake more appropriate in a business setting.

Why touch matters

Touch is important for bonding and communications: "Touch is universal. While culture does modulate how we experience it, generally we all respond to touching in the same ways. Even in an era of mobile communications and social media, touch is still important for establishing and maintaining the bonds between people," says Oxford University's professor Robin Dunbar in a release.

Confused about what is and isn't appropriate?

There's one kind of social touching that's almost always appropriate: “Upon greeting a stranger, offering to shake hands is the most standard gesture and is appropriate for both social and professional meetings. A handshake is never viewed as rude, and carries little risk of making anybody feel uncomfortable," Debby Hume, a spokesperson at Debrett's, a business etiquette school in the U.K., told The Telegraph.

If you want to err on the side of caution, keep the cheek kisses, air kisses, hugs and shoulder-touching out of the picture until you know someone a bit better. Until then, a handshake will do the trick.

Starre Vartan ( @ecochickie ) covers conscious consumption, health and science as she travels the world exploring new cultures and ideas.