Whether you're a casual user of social media sites like facebook and twitter or an avid online dater accessing eHarmony or Match.com, chances are you've created a personal online profile and been faced with a decision: What should you post for your profile picture? Many people post head shots or selfies, while others opt for pictures of their children, spouses, pets, or even favorite quotes or symbols. If your goal is to be perceived as attractive (and let's be honest, whose isn't?), then new research by Drew Walker and Edward Vul at the University of California, San Diego suggests your best bet is to opt for a group shot with friends.

A photo with friends conveys the fact that you are amiable and well-liked, but oddly enough that is not what makes you more appealing. Instead, the new research shows that individual faces appear more attractive when presented in a group than when presented alone — a perceptually driven phenomenon known as the cheerleader effect.

Consider the Laker girls or Dallas Cowboy Cheerleaders. To many, these women are beautiful and sexy. However, their perceived beauty is in part a visual illusion, created by the fact that cheerleaders appear as a group rather than solo operators. Any one cheerleader seems far more attractive when she is with her team than when she is alone.

This visual illusion is mediated by similar cognitive and perceptual processes that underlie other well-known visual illusions like the Ebbinghaus illusion or the moon illusion. With the Ebbinghaus illusion, a medium-sized dot appears much larger when surrounded by a field of smaller dots, but appears much smaller when surrounded by a field of larger dots. The moon illusion is the perception that the moon seems larger when it appears on the horizon than up in the sky. All of these visual illusions demonstrate that what we "see" is not always a simple or direct reflection of what is right in front of us. Instead, what we see depends on both the physical stimulus coded by our visual systems (what cognitive scientists refer to as bottom up processing), and a blend of contextual information, expectations, and prior knowledge (known as top down processing).

Walker and Vul posit that the cheerleader effect arises from the interplay of three different visuo-cognitive processes. First, whenever we view a set of objects like an array of dots or a group of faces, our visual system automatically computes general information about the entire set, including average size of group members, their average location, and even the average emotional expression on faces. Thus although the group contains many individual items, we naturally perceive those items as a set, and form our impressions on the basis of the collective whole.

In addition, the impression that we have of the group as a whole influences our perception of any one individual item. We tend to view individual members as being more like the group than they actually are. Thus when we see a face in a crowd, we tend to perceive that face as similar to the average of all the faces in that crowd.

As it turns out, we find average faces very attractive. Composite faces, which are generated by averaging individual faces together, are rated as significantly more attractive than the individual faces used to create them. According to Walker and Vul, if presenting a face in a group causes us to perceive that face as more similar to the average, we are likely to find that face more attractive.

To test this theory, Walker and Vul conducted a series of experiments in which participants rated the attractiveness of faces that appeared in a group or individually. In two of their studies, the group photographs included three male or three female faces together in the same scene. The individual portraits of each face were cropped from those group photographs. Participants rated each face twice, once when presented as part of the group photo, and once as an individual portrait, though the order of these ratings was randomized across participants. Both male and female faces were rated as more attractive when they appeared as part of a group photo than as a solo portrait.

Although these findings are consistent with a perceptual interpretation of the cheerleader effect, it is possible that people preferred the faces that appeared in a group because the group scene also conveyed critical social or emotional information. To address this possibility, another study was conducted in which the group photographs were constructed by assembling individual faces, each photographed separately, in a collective matrix. Again participants rated the attractiveness of each face both when it was part of a group and as an individual portrait. And again the faces were rated as more attractive when they appeared with other faces than when they appeared alone. Notably, the effect disappears when the group array consists of the same face multiple times, suggesting that it is indeed the averaging of many different faces that produces the effect.

Clearly a group photo is the way to go if you want to enhance your personal appeal. But how big does the group need to be? Walker and Vul reasoned that increasing group size should yield a more precise average, and that precise average should exert a greater influence on any one individual face. They thus predicted that faces that appeared in a large group would be rated as more attractive than those that appeared in a small group. To their surprise, attractiveness ratings did not differ for faces rated in groups of 4, 9, or 16. It seems that a small cadre of cronies may be enough to elevate your allure.

Although the current studies only assessed attractiveness ratings for photographs, the perceptual processes that mediate the cheerleader effect should function similarly regardless of whether you are interacting via facebook or face-to-face. These processes operate on an automatic level, are evident for inanimate and animate objects, and are difficult to override, even when we are aware that our eyes are lying to us. So whether you are dating online or in the flesh, take a page from the cheerleaders: Bring along some wingwomen (or wingmen).

Are you a scientist who specializes in neuroscience, cognitive science, or psychology? And have you read a recent peer-reviewed paper that you would like to write about? Please send suggestions to Mind Matters editor Gareth Cook, a Pulitzer prize-winning journalist and regular contributor to NewYorker.com. Gareth is also the series editor of Best American Infographics, and can be reached at garethideas AT gmail.com or Twitter @garethideas.