An analysis of the PAIRFAM data found that friends with more similar demographic characteristics, such as age and gender, tended to report somewhat higher emotional closeness. This association was stronger among women than among men. The paper was published in the Journal of Social and Personal Relationships.
The similarity-attraction hypothesis proposes that people are generally more likely to feel attracted to those who resemble them in important ways. Similarity may involve attitudes, values, interests, personality traits, education, cultural background, or lifestyle. In interpersonal relationships, shared characteristics can make communication easier and interactions more predictable. Discovering that another person agrees with us may also validate our beliefs and strengthen our positive feelings toward them.
Similarity can therefore influence the formation of friendships, romantic relationships, and professional connections. It may also promote relationship stability because similar partners often have compatible goals, habits, and expectations. However, attraction does not require complete similarity, and some differences can be appealing or complementary when they do not create major conflicts.
The study author, Markus Jokela, tested the similarity-attraction hypothesis by exploring whether sociodemographic similarity between friends is associated with their emotional closeness. Sociodemographic similarity refers to sharing social and statistical characteristics, such as age, income, education, or marital status. He also explored whether individuals with certain personality traits from the Big Five model of personality are more likely to report higher emotional closeness with their friends.
He analyzed data from the Panel Analysis of Intimate Relationships and Family Dynamics, known as PAIRFAM. PAIRFAM is a German family panel study. A panel study is a type of research that observes the exact same group of people repeatedly over a long period of time. This study started back in 2008 with a national sample of 12,000 people from three birth cohorts, or groups of people born around the same time: those born between 1991 and 1993, between 1981 and 1983, and between 1971 and 1973. This analysis included all participants from waves 2 and 4 of the PAIRFAM study for whom personality data were available, totaling 7,699 participants. In long-term research, a wave refers to a specific round or year of data collection.
The average age of the participants was 26 years. Slightly less than 84 percent of them were native Germans or ethnic German immigrants, and 53 percent of the participants were women.
Data on friends were collected by asking participants to name individuals in their lives with whom they (1) shared personal thoughts or feelings, (2) had regular meetings for activities, (3) got help with information or advice in practical matters, or (4) occasionally quarreled or had conflicts. Participants listed up to 30 people in response to this question.
Participants reported emotional closeness to each of these individuals by answering the question, “How close do you feel to [name person]?” They also reported various demographic data for each of these friends, including sex, age, marital status, and whether the friend had children under 3 years of age. This allowed the study author to calculate the demographic similarity between the participant and each of their friends.
Aside from this, participants completed an assessment of the Five Factor Model personality traits, using a 21-item survey known as the Big Five Inventory. The Big Five model describes personality through five broad dimensions. For clarity, openness to experience involves being curious and creative; conscientiousness means being organized and responsible; extraversion refers to being outgoing and energetic; agreeableness involves being friendly and cooperative; and neuroticism is the tendency to experience negative emotions like anxiety or sadness.
The results showed that participants tended to rate their friends who were more demographically similar to them as somewhat emotionally closer. More specifically, participants tended to be emotionally closer to friends who were the exact same age. This was the case for both men and women. Women tended to rate their friends of the same sex as emotionally closer than their male friends.
Among men, the sex of a friend was not associated with emotional closeness. Sharing the same parenthood status was related to higher closeness for men, but surprisingly, it was related to lower closeness for women. Sharing the same marital status was also related to emotional closeness, but this association was very weak.
Participants who scored higher in the personality traits of extraversion, agreeableness, conscientiousness, and openness to experience tended to report higher emotional closeness with their friends.
The study author concluded that findings from this large German cohort study provide extended support for the similarity-attraction hypothesis. The results show that people do not just have friends who share sociodemographic similarities, but that these similarities are also tied to emotionally closer relationships with those friends. Additionally, personality differences, extraversion in particular, are associated with emotional closeness, and friend similarity may amplify some of these associations.
This study contributes to the scientific understanding of interpersonal relationships. However, it should be noted that the study participants were mostly young Germans, meaning the results in other ethnic or age groups might differ. Additionally, the design of the study does not allow any causal inferences to be derived from the results. In this case, while similarity and closeness are linked, the study cannot prove that being similar is the cause of the emotional closeness.
The paper, “Emotional Closeness with Friends Is Associated With Sociodemographic Similarity and Personality Traits,” was authored by Markus Jokela.