characteristics, life goals and physical appearance. The more these points match, the happier, satisfied and prosperous people are in these relationships. The lookalike effect plays the role of self-affirmation. A person typically enjoys receiving confirmation of aspects of his or her life, ideas, attitudes and personal characteristics, and people seem to look for an image of themselves to spend their life with. A basic principle of interpersonal attraction is the rule of similarity: similarity is attractive — an underlying principle that applies to both friendships and romantic relationships. The proportion of attitudes shared correlates well with the degree of interpersonal attraction. Cheerful people like to be around other cheerful people and negative people would rather be around other negative people. A 2004 study, based on indirect evidence, concluded that humans choose mates based partly on facial resemblance to themselves. According to Morry's attraction-similarity model (2007), there is a lay belief that people with actual similarity produce initial attraction. The perceived similarity is either self-serving, as in a friendship, or relationship-serving, as in a romantic relationship. In a 1963 study, Theodore Newcomb pointed out that people tend to change perceived similarity to obtain balance in a relationship. Additionally, perceived but not actual similarity was found to predict interpersonal attraction during a face-to-face initial romantic encounter. In a 1988 study, Lydon, Jamieson & Zanna suggest that interpersonal similarity and attraction are multidimensional constructs in which people are attracted to people similar to themselves in demographics, physical appearance, attitudes, interpersonal style, social and cultural background, personality, preferred interests and activities, and communication and social skills. Newcomb's earlier 1961 study on college-dorm roommates also suggested that individuals with shared backgrounds, academic achievements, attitudes, values, and political views typically became friends. Physical appearance The matching hypothesis proposed by sociologist Erving Goffman suggests that people are more likely to form long standing relationships with those who are equally matched in social attributes, like physical attractiveness. The study by researchers Walster and Walster supported the matching hypothesis by showing that partners who were similar in terms of physical attractiveness expressed the most liking for each other. Another study also found evidence that supported the matching hypothesis: photos of dating and engaged couples were rated in terms of attractiveness, and a definite tendency was found for couples of similar attractiveness to date or engage. Several studies support this evidence of similar facial attractiveness. Penton-Voak, Perrett and Peirce (1999)