If you’ve ever online dated, you know how important your picture can be in attracting people to view your profile and in initiating contact. OkCupid recently did a study of over 7,000 subscribers to see what kinds of photos drew the most interest, which ones performed worst, and which common beliefs turned out to be wrong. A profile picture can do a lot of work before anyone reads a word you write. The results are full of surprising patterns, and they are worth keeping in mind.

Contrary to popular opinion, women do like men to be shirtless, but it comes with an age limit. If the guy is older than 31, he gets far fewer responses than younger men, especially those around 18. Men with nicer abs also get more attention than men with less defined bodies. Age seems to matter almost as much as appearance in this case. In other words, if you are young and fit, showing it off online can help.

Men prefer women who smile in their photos, while women prefer men who are not smiling and may even be looking away from the camera. Maybe that is because people are often drawn to mystery. At the same time, both men and women seem turned off by flirty faces that do not look directly at the camera. A simple expression can change the whole tone of a profile. Small changes in expression can make a bigger difference than many people expect.

The shot, where the picture is taken from above, is the most effective photo a woman can use. It may seem like cleavage would matter most, but the study found no extra response from cleavage shots compared with photos that did not show it. A picture of a woman doing something interesting, like playing guitar or rock climbing, can lead to more messages and longer conversations than a sexy shot. Photos that give people something to ask about have more staying power.