Pause a moment and think about your relationships with two people—a close friend, and someone who has stirred your feelings of romantic love. What psychological chemistry binds us together in these special attachments? Social psychology suggests some answers.

45-1 Why do we befriend or fall in love with some people but not others?

We endlessly wonder how we can win others’ affection and what makes our own affections flourish or fade. Does familiarity breed contempt, or does it amplify affection? Do birds of a feather flock together, or do opposites attract? Is beauty only skin deep, or does physical attractiveness matter greatly? To explore these questions, let’s consider three ingredients of our liking for one another: proximity, attractiveness, and similarity.

ProximityBefore friendships become close, they must begin. Proximity—geographic nearness—is friendship’s most powerful predictor. Proximity provides opportunities for aggression, but much more often it breeds liking. Study after study reveals that people are most inclined to like, and even to marry, those who live in the same neighborhood, who sit nearby in class, who work in the same office, who share the same parking lot, who eat in the same dining hall. Look around. Mating starts with meeting.

Proximity breeds liking partly because of the mere exposure effect. Repeated exposure to novel stimuli increases our liking for them. This applies to nonsense syllables, musical selections, geometric figures, Chinese characters, human faces, and the letters of our own name (Moreland & Zajonc, 1982; Nuttin, 1987; Zajonc, 2001). We are even somewhat more likely to marry someone whose first or last name resembles our own (Jones et al., 2004).

So, within certain limits, familiarity feeds fondness (Bornstein, 1989, 1999). Researchers demonstrated this by having four equally attractive women silently attend a 200-student class for zero, 5, 10, or 15 class sessions (Moreland & Beach, 1992). At the end of the course, students viewed slides of each woman and rated her attractiveness. The most attractive? The ones they’d seen most often. The phenomenon would come as no surprise to the young Taiwanese man who wrote more than 700 letters to his girlfriend, urging her to marry him. She did marry—the mail carrier (Steinberg, 1993).

No face is more familiar than your own. And that helps explain an interesting finding by Lisa DeBruine (2004): We like other people when their faces incorporate some morphed features of our own. When DeBruine (2002) had McMaster University students (both men and women) play a game with a supposed other player, they were more trusting and cooperative when the other person’s image had some of their own facial features morphed into it. In me I trust. (See also FIGURE 45.1.)

For our ancestors, the mere exposure effect had survival value. What was familiar was generally safe and approachable. What was unfamiliar was more often dangerous and threatening. Evolution may therefore have hard-wired into us the tendency to bond with those who are familiar and to be wary of those who are unfamiliar (Zajonc, 1998). If so, gut-level prejudice against those who are culturally different could be a primitive, automatic emotional response (Devine et al., 2012). It’s what we do with our knee-jerk prejudice that matters, say researchers. Do we let those feelings control our behavior? Or do we monitor our feelings and act in ways that reflect our conscious valuing of human equality?

Modern MatchmakingThose who have not found a romantic partner in their immediate proximity may cast a wider net by joining an online dating service. Published research on Internet matchmaking effectiveness is sparse. But this much seems well established: Some people, including occasional predators, dishonestly represent their age, attractiveness, occupation, or other details, and thus are not who they seem to be. Nevertheless, Katelyn McKenna and John Bargh and their colleagues have offered a surprising finding: Compared with relationships formed in person, Internet-formed friendships and romantic relationships are, on average, slightly more likely to last and be satisfying (Bargh et al., 2002, 2004; Cacioppo et al., 2013; McKenna et al., 2002). In one of their studies, people disclosed more, with less posturing, to those whom they met online. When conversing online with someone for 20 minutes, they felt more liking for that person than they did for someone they had met and talked with face to face. This was true even when (unknown to them) it was the same person! Internet friendships often feel as real and important to people as in-person relationships. Small wonder that the historic ways couples have met—at school, on the job, through family, or, especially, through friends—have been supplemented by a striking rise in couples who meet over the Internet. In a recent national survey of straight and gay/lesbian couples, nearly a quarter of heterosexual couples and some two-thirds of same-sex couples met online (Rosenfeld & Thomas, 2012; see FIGURE 45.2).

Speed dating pushes the search for romance into high gear. In a process pioneered by a matchmaking Jewish rabbi, people meet a succession of prospective partners, either in person or via webcam (Bower, 2009). After a 3- to 8-minute conversation, people move on to the next prospect. (In an in-person meeting, one partner—usually the woman—remains seated and the other circulates.) Those who want to meet again can arrange for future contact. For many participants, 4 minutes is enough time to form a feeling about a conversational partner and to register whether the partner likes them (Eastwick & Finkel, 2008a,b).

For researchers, speed dating offers a unique opportunity for studying influences on our first impressions of potential romantic partners. Among recent findings are these:

Physical AttractivenessOnce proximity affords us contact, what most affects our first impressions? The person’s sincerity? Intelligence? Personality? Hundreds of experiments reveal that it is something far more superficial: physical appearance. This finding is unnerving for those of us taught that “beauty is only skin deep” and “appearances can be deceiving.”

In one early study, researchers randomly matched new University of Minnesota students for a Welcome Week dance (Walster et al., 1966). Before the dance, the researchers gave each student a battery of personality and aptitude tests, and they rated each student’s physical attractiveness. During the blind date, the couples danced and talked for more than two hours and then took a brief intermission to rate their dates. What determined whether they liked each other? Only one thing seemed to matter: appearance. Both the men and the women liked good-looking dates best. Women are more likely than men to say that another’s looks don’t affect them (Lippa, 2007). But studies show that a man’s looks do affect women’s behavior (Eastwick et al., 2014a,b). Speed-dating experiments confirm that attractiveness influences first impressions for both sexes (Belot & Francesconi, 2006; Finkel & Eastwick, 2008).

Physical attractiveness also predicts how often people date and how popular they feel. It affects initial impressions of people’s personalities. We don’t assume that attractive people are more compassionate, but research participants perceive them as healthier, happier, more sensitive, more successful, and more socially skilled (Eagly et al., 1991; Feingold, 1992; Hatfield & Sprecher, 1986). Attractive, well-dressed people have been more likely to make a favorable impression on potential employers, and they have tended to be more successful in their jobs (Cash & Janda, 1984; Langlois et al., 2000; Solomon, 1987). Income analyses show a penalty for plainness or obesity and a premium for beauty (Engemann & Owyang, 2005).

Even babies have preferred attractive over unattractive faces (Langlois et al., 1987). So do some blind people, as University of Birmingham professor John Hull (1990, p. 23) discovered after going blind. A colleague’s remarks on a woman’s beauty would strangely affect his feelings. He found this “deplorable.… What can it matter to me what sighted men think of women … yet I do care what sighted men think, and I do not seem able to throw off this prejudice.”

For those who find the importance of looks unfair and unenlightened, two findings may be reassuring. First, people’s attractiveness is surprisingly unrelated to their self-esteem and happiness (Diener et al., 1995; Major et al., 1984). Unless we have just compared ourselves with superattractive people, few of us (thanks, perhaps, to the mere exposure effect) view ourselves as unattractive (Thornton & Moore, 1993). Second, strikingly attractive people are sometimes suspicious that praise for their work may simply be a reaction to their looks. Less attractive people have been more likely to accept praise as sincere (Berscheid, 1981).

Beauty is also in the eye of the culture. Hoping to look attractive, people across the globe have pierced and tattooed their bodies, lengthened their necks, bound their feet, and dyed their hair. They have gorged themselves to achieve a full figure or liposuctioned fat to achieve a slim one, applied chemicals hoping to rid themselves of unwanted hair or to regrow wanted hair, strapped on leather garments to make their breasts seem smaller or surgically filled their breasts with silicone and worn Wonderbras to make them look bigger. Cultural ideals change over time. For women in North America, the ultra-thin ideal of the Roaring Twenties gave way to the soft, voluptuous Marilyn Monroe ideal of the 1950s, only to be replaced by today’s lean yet busty ideal.

Some aspects of attractiveness, however, do cross place and time (Cunningham et al., 2005; Langlois et al., 2000). By providing reproductive clues, bodies influence sexual attraction. As evolutionary psychologists explain, men in many cultures, from Australia to Zambia, judge women as more attractive if they have a youthful, fertile appearance, suggested by a low waist-to-hip ratio (Karremans et al., 2010; Perilloux et al., 2010; Platek & Singh, 2010). (I [DM] always thought my wife looked cute in her genes.) Women feel attracted to healthy-looking men, but especially—and more so when ovulating—to those who seem mature, dominant, masculine, and affluent (Gallup & Frederick, 2010; Gangestad et al., 2010). But faces matter, too. When people rate opposite-sex faces and bodies separately, the face tends to be the better predictor of overall physical attractiveness (Currie & Little, 2009; Peters et al., 2007).

People everywhere also seem to prefer physical features—noses, legs, physiques—that are neither unusually large nor small. An averaged face is attractive (FIGURE 45.3). In one clever demonstration, researchers digitized the faces of up to 32 college students and used a computer to average them (Langlois & Roggman, 1990). Students judged the averaged, composite faces as more attractive than 96 percent of the individual faces. One reason is that averaged faces are symmetrical, and people with symmetrical faces and bodies are more sexually attractive (Rhodes et al., 1999; Singh, 1995; Thornhill & Gangestad, 1994). Merge either half of your face with its mirror image and your symmetrical new face would boost your attractiveness a notch.

Our feelings also influence our attractiveness judgments. Imagine two people. The first is honest, humorous, and polite. The second is rude, unfair, and abusive. Which one is more attractive? Most people perceive the person with the appealing traits as more physically attractive (Lewandowski et al., 2007). Those we like we find attractive. In a Rodgers and Hammerstein musical, Prince Charming asks Cinderella, “Do I love you because you’re beautiful, or are you beautiful because I love you?” Chances are it’s both. As we see our loved ones again and again, their physical imperfections grow less noticeable and their attractiveness grows more apparent (Beaman & Klentz, 1983; Gross & Crofton, 1977). Shakespeare said it in A Midsummer Night’s Dream: “Love looks not with the eyes, but with the mind.” Come to love someone and watch beauty grow.

SimilaritySo proximity has brought you into contact with someone, and your appearance has made an acceptable first impression. What influences whether you will become friends? As you get to know each other, will the chemistry be better if you are opposites or if you are alike?

It makes a good story—extremely different types liking or loving each other: Rat, Mole, and Badger in The Wind in the Willows, Frog and Toad in Arnold Lobel’s books, Edward and Bella in the Twilight series. The stories delight us by expressing what we seldom experience. In real life, opposites retract (Rosenbaum, 1986; Montoya & Horton, 2013). Compared with randomly paired people, friends and couples are far more likely to share common attitudes, beliefs, and interests (and, for that matter, age, religion, race, education, intelligence, smoking behavior, and economic status).

Moreover, the more alike people are, the more their liking endures (Byrne, 1971). Journalist Walter Lippmann was right to suppose that love lasts “when the lovers love many things together, and not merely each other.” Similarity breeds content. One app therefore matches people with potential dates based on their proximity, and on the similarity of their Facebook profiles.

Proximity, attractiveness, and similarity are not the only determinants of attraction. We also like those who like us. This is especially true when our self-image is low. When we believe someone likes us, we feel good and respond to them warmly, which leads them to like us even more (Curtis & Miller, 1986). To be liked is powerfully rewarding.

Indeed, all the findings we have considered so far can be explained by a simple reward theory of attraction: We will like those whose behavior is rewarding to us, including those who are both able and willing to help us achieve our goals (Montoya & Horton, 2014). When people live or work in close proximity to us, it requires less time and effort to develop the friendship and enjoy its benefits. When people are attractive, they are aesthetically pleasing, and associating with them can be socially rewarding. When people share our views, they reward us by validating our beliefs.

45-2 How does romantic love typically change as time passes?

Sometimes people move quickly from initial impressions, to friendship, to the more intense, complex, and mysterious state of romantic love. If love endures, temporary passionate love will mellow into a lingering companionate love (Hatfield, 1988).

Passionate LoveA key ingredient of passionate love is arousal. The two-factor theory of emotion can help us understand this intense positive absorption in another (Hatfield, 1988). That theory assumes that

Arousal can come from within, as we experience the excitement of a new relationship. But in tests of the two-factor theory, college men have been aroused by fright, by running in place, by viewing erotic materials, or by listening to humorous or repulsive monologues. They were then introduced to an attractive woman and asked to rate her (or their girlfriend). Unlike unaroused men, the stirred-up men attributed some of their arousal to the woman or girlfriend, and felt more attracted to her (Carducci et al., 1978; Dermer & Pyszczynski, 1978; White & Kight, 1984).

A sample experiment: Researchers studied people crossing two bridges above British Columbia’s rocky Capilano River (Dutton & Aron, 1974, 1989). One, a swaying footbridge, was 230 feet above the rocks; the other was low and solid. The researchers had an attractive young woman intercept men coming off each bridge, and ask their help in filling out a short questionnaire. She then offered her phone number in case they wanted to hear more about her project. Far more of those who had just crossed the high bridge—which left their hearts pounding—accepted the number and later called the woman. To be revved up and to associate some of that arousal with a desirable person is to feel the pull of passion. Adrenaline makes the heart grow fonder. And when sexual desire is supplemented by a growing attachment, the result is the passion of romantic love (Berscheid, 2010).

Companionate LoveAlthough the desire and attachment of romantic love often endure, the intense absorption in the other, the thrill of the romance, the giddy “floating on a cloud” feelings typically fade. Does this mean the French are correct in saying that “love makes the time pass and time makes love pass”? Or can friendship and commitment keep a relationship going after the passion cools?

As love matures, it typically becomes a steadier companionate love—a deep, affectionate attachment (Hatfield, 1988). The flood of passion-facilitating hormones (testosterone, dopamine, adrenaline) subsides and another hormone, oxytocin, supports feelings of trust, calmness, and bonding with the mate. In the most satisfying of marriages, attraction and sexual desire endure, minus the obsession of early stage romance (Acevedo & Aron, 2009).

There may be adaptive wisdom to the shift from passion to attachment (Reis & Aron, 2008). Passionate love often produces children, whose survival is aided by the parents’ waning obsession with each other. Failure to appreciate passionate love’s limited half-life can doom a relationship (Berscheid et al., 1984). Indeed, recognizing the short duration of obsessive passionate love, some societies deem such feelings to be an irrational reason for marrying. Better, they say, to choose (or have someone choose for you) a partner with a compatible background and interests. Non-Western cultures, where people rate love as less important for marriage, do have lower divorce rates (Levine et al., 1995).

One key to a gratifying and enduring relationship is equity. When equity exists—when both partners receive in proportion to what they give—their chances for sustained and satisfying companionate love are good (Gray-Little & Burks, 1983; Van Yperen & Buunk, 1990). In one national survey, “sharing household chores” ranked third, after “faithfulness” and a “happy sexual relationship,” on a list of nine things people associated with successful marriages. “I like hugs. I like kisses. But what I really love is help with the dishes,” summarized the Pew Research Center (2007).

Equity’s importance extends beyond marriage. Mutually sharing one’s self and possessions, making decisions together, giving and getting emotional support, promoting and caring about each other’s welfare—all of these acts are at the core of every type of loving relationship (Sternberg & Grajek, 1984). It’s true for lovers, for parent and child, and for close friends.

Another vital ingredient of loving relationships is self-disclosure, the revealing of intimate details about ourselves—our likes and dislikes, our dreams and worries, our proud and shameful moments. “When I am with my friend,” noted the Roman statesman Seneca, “me thinks I am alone, and as much at liberty to speak anything as to think it.” Self-disclosure breeds liking, and liking breeds self-disclosure (Collins & Miller, 1994). As one person reveals a little, the other reciprocates, the first then reveals more, and on and on, as friends or lovers move to deeper levels of intimacy (Baumeister & Bratslavsky, 1999).

One experiment marched student pairs through 45 minutes of increasingly self-disclosing conversation—from “When did you last sing to yourself?” to “When did you last cry in front of another person? By yourself?” Others spent the time with small-talk questions, such as “What was your high school like?” (Aron et al., 1997). By the experiment’s end, those experiencing the escalating intimacy felt much closer to their conversation partner than did the small-talkers.

Intimacy can also grow when we pause to ponder and write our feelings. Researchers invited one person from each of 86 dating couples to spend 20 minutes a day over three days either writing their deepest thoughts and feelings about the relationship or writing merely about their daily activities (Slatcher & Pennebaker, 2006). Those who wrote about their feelings expressed more emotion in their instant messages with their partners in the days following, and 77 percent were still dating three months later (compared with 52 percent of those who had written about their activities).

In addition to equity and self-disclosure, a third key to enduring love is positive support. While relationship conflicts are inevitable, we can ask ourselves whether our communications more often express sarcasm or support, scorn or sympathy, sneers or smiles. For unhappy couples, disagreements, criticisms, and put downs are routine. For happy couples in enduring relationships, positive interactions (compliments, touches, laughing) outnumber negative interactions (sarcasm, disapproval, insults) by at least 5 to 1 (Gottman, 2007; see also Sullivan et al., 2010).

In the mathematics of love, self-disclosing intimacy + mutually supportive equity = enduring companionate love.