Motivation and emotion/Book/2013/Motivation and relationships

Overview
It has long been hypothesised that men are attracted to physical appearance and women place a higher importance on personality, character and other 'skin-deep' qualities, there is a large body of research to support this popular idea (Stroebe, Insko, Thompson, & Layton, 1971). With the growing acceptance of psychology and drive to understand what makes us who we are, its important to get it right when it comes to relationships especially because we could be in them for quite a while!

Often we attribute the 'opposites attract' idea to relationships between different people but In reality, research says this may be the case for short-term relationships or flings but when it comes to long-term relationships 'positive correlations have been found between their race, socioeconomic status, age, intellectual ability, education, personality variables, physical attractiveness, vocational interest and anthropometric measures' (Ahern et al., 1985; Bereczkei, & Casanaky, 1996; Bereczkei, & Vörös, 1997; Jaffe & Chacon-Puignau, 1995; Keller et al., 1996, Mascie-Taylor, 1988; Mascie-Taylor, 1995; Penton-Voak et al., 1999; Susanne & Lepage, 1988 and Thiessen et al., 1997, as cited in Bereczkei, Gyuris, Koves, & Bernath, 2002).

According to the 'law of attraction' by Byrne (1971) people are attracted to others with similar attitudes and based on cognitive consistency theories, similarity in attitudes promotes social attraction (Byrne, London, & Reeves, 1968). Furthermore, according to studies by Jacobs, Berscheid, and Walster (1971) and Byrne and Griffitt (1973) people are more attracted to those who share similar attitudes in general people are most attracted to others who share similar attitudes. It was also found that people who share similar attitudes on issues perceived as important are more likely to be attracted to each other than those who share perceived less important attitudes. Research also suggests this is the same for same sex friendships with DeBruine (2002, as cited in Watkins, DeBruine, Smith, Jones, Vukovic, & Fraccaro, 2011) finding self-resemblance in same-sex faces positively correlated with co-operation in economic games.

Science and psychology has had a large input in this area, research by Bereczkei, Gyuris, Koves and Bernath (2002) found people tend to gravitate towards those who are not only homogamous in social attitudes but also genetically. Studies have also found that children are more attracted to similar phenotypes possessed by the opposite sex parent (Bereczkei et al., 2002; Watkins et al., 2011). Explanations for this vary from emotional closeness to the opposite sex parent as a predictor for the same phenotype preferences in partners to offspring who display phenotypes more like their opposite sex parents have a better relationship with them and the reason they select mates with the same phenotypes is because of resemblance to themselves (Bereczkei et al., 2002; Little, Penton-Voak, Burt, & Pettett, 2003; Watkins et al., 2011; Wiszewska, pawlowki, & Boothroyd, 2007).

This chapter will focus on long term mate selection for the heterosexual population with the majority of research centered around American and European studies. Please see the other Motivation and emotion 2913 - how to improve your life chapters on sexual orientation and how to get more sex for research on the homosexual, bisexual and asexual population.

Hamilton's kin selection theory
Hamilton (1969) proposed that humans favour the reproductive success of close relatives genes when selecting a mate and direct altruistic behaviours towards those who share genes, it was considered an extension of Darwin's 'survival of the fittest'.

Known as ' Hamilton's rule ', C< r X B where C = cost in fitness to the giver, r = the genetic relationship between the giver and the recipient, and B = fitness benefit to the recipient (Hamilton, 1969). A critique of his theory and equation is that the overall proportion of genes shared by individuals is irrelevant unless genes are shared for altruism (Mealy, 1985, as cited in Bereczkei, Gyuris, Koves & Bernath, 2002).

Thiessen and Gregg (1980) research (as cited in Bereczkei et al., 2002) provides an extension of Hamilton's theory and argued that it wasn't a case of protecting family genes from strangers but that humans have the ability to detect other genetically similar organisms who are not close relatives (Bereczkei et al., 2002). This was supported by positive assortment, whereby the degree to which parents share genes with offspring would be increased. Parents with identical genes will add 50% of their genes to the offspring PLUS sections of genes held in common by both parents (Bereczkei et al., 2002).

Genetic similarity theory
This theory suggests that due to the fitness gains associated with homogamy, humans have a complex psychological mechanism that is able to detect similar genes in and direct altruistic behaviour towards them, both in romantic pursuit and friendship (Bereczkei et al., 2002). Supporting research has found an innate ability to detect personal phenotype's and link them to unrelated strangers. Porter (1987) found that mothers who had limited contact with their newborn child were able to detect them purely by smell (Bereczkei et al., 2002). Similarly, Christenfeld & Hill (1995) presented participants with mixed photographs of newborn infants, mothers and fathers and asked participants to match, results yielded positively supporting an inbuilt mechanism for genetic detection (Bereczkei et al., 2002).

Phenotype matching refers to the use of sensory modalities to detect similar others (Watkins et al., 2011). Self-referential phenotype matching is supported by studies using computer generated self-resembling faces and preference for the strongest resembling faces (Bressan & Zucchi, 2009, as cited in Watkins et al., 2011).

Criticisms of this theory include theoretical problems with phenotype matching (Wilson, 1989 as cited in Bereczkei et al., 2002). Research has shown that discriminatory altruism on the basis of phenotype similarity is uncorrelated with the likelihood of sharing altruism allele, as a result genetic similarity theory isn't appropriate when predicting when altruism should occur between unrelated individuals (Daly, Salmos & Wilson, 1997; Hepper 1989, as cited in Bereczkei et al., 2002).

Evolutionary theory of homogamy
Is a scientific theory that people and animals tend to select mates who look similar to themselves. There are several studies providing supporting evidence, assortative mating is found to have advantages including enhanced marital stability and fertility. Studies have shown married couples were more genetically similar than other randomly paired individuals, with the majority of overlapping coming from the areas of certain physical traits, personality and cognitive factors (Buunk & Frees, 1997; Rushton, 1988; Rushton & Nicholson, 1988; Russell, Wells & Rshton, 1985; Tesser, 1993, as cited in Bereczkei et al.,2002).

Emotional efference
Is a theory that emotional processes produce long-lasting vascular changes that are regulated by facial musculature. Over time it is proposed that use of certain facial muscles changes the physical look of the face (Zajonc, Adelmann, Murphy, & Niedenthal, 1987). In the context of this chapter, it has been hypothesised that couples who spend more time together tend to converge in looks through using the same facial responses to situations (Zajonc et al. 1987).

Uncertainty of paternity
Is a theory that suggests men are driven by anxiety of paternity uncertainty post child birth when selecting mates (Bovet, Barthes, Durand, Raymond, & Alvergne, 2012). It suggests men preference women with recessive genes compared to themselves so the phenotype of offspring will have more paternal traits so they can detect their own children and pass on kin genetics (Bovet et al., 2012). On the other hand, a man with recessive genes will preference a woman with the same recessive genes to ensure the same phenotype in offspring, failure to display those genes would mean it was not their offspring (Bovet et al., 2012).

Optimal in-breeding
Bateson (1983) conducted research (as cited in Bereczkei et al., 2002) that argues sexual imprinting allows people to learn phenotype characteristics of close family which allows then to select mates that look similar but are not too genetically close. This is a balance between inbreeding and outbreeding to get optimal reproductive results. Bereczkei et al. (2002) cites supporting evidence from Japanese quail that select mates with a slightly different colour to their parents (Bateson, 1979, 1980, 1988).

Strategic Pluralism Theory
According to strategic pluralism theory, women looking for short-term mates consider physical attractiveness as the most important element this is because they are looking for the best genes to pass onto their offspring (Gangestad & Simpson, 2000 as cited in Li, & Kenrick, 2006). Moreover, men that women consider physically attractive have symmetrical and masculine faces, men with these characteristics also have more sexual partners (Li & Kenrick, 2006). According to Li and Kenrick (2006) preference for short term mates among men and women is similar, in line with the theory they need to be physically attractive.

Physical similarity
Cross-culturally averageness and symmetry of faces are seen as attractive and reveal deeper biologically relevant traits important to mating such as health, reproductive potential and parenting behaviours (Laeng, Vermeer, & Sulutvedt, 2013; Bovet et al., 2012). In a study by Laeng et al. (2013) participants were presented with facial images of the opposite sex that have been 'morphed' to look like the participant and partner (See figure 1). Results found only a tolerance for 22% of their partners face to be 'morphed' with another and participants favoured the 'self-based morph' (their partners face with a small amount of their own face blended into it).

Another study focussed on male mate selection used computer generated images to find out if men preferred women with recessive traits in support of the uncertainty of paternity hypothesis or if they preferred self-resembling traits in support of theories of homogamy (Bovet et al., 2012). The study found men prefer self-resembling facial traits in partners in both the experimental setting and in reality (Bovet et al., 2012). There was no support for the uncertainty of paternity hypothesis (Bovet et al., 2012).

It would seem we know our own physical attractiveness and limits when it comes to dating. Stroebe et al. (1971) found that those who rated themselves less attractive considered other unattractive participants for dates more so than the attractive ones. Furthermore, perception of facial attractiveness appears to be independent of cultural backgrounds, infants from a variety of ethnicities have been found to favour the more adult perceived attractive faces than the unattractive ones by looking longer at the attractive ones (Langlois, Ritter, Roggman, & Vaughan, 1991, as cited in Rashidi, Pazhoohi, & Hosseinchari, 2012).

Physical convergence
While the reasons humans may be attracted to similar looking people has been vastly explored in social psychology and science, there is very little research in the way of convergence in physical appearance of couples over time. Zajonc et al., (1987) published a 25 year longitudinal study that hypothesised partner resemblance may not only be attributed to common genes but also long-term social contact. Results found higher resemblance after 25 years of marriage than at the time of marriage. The researchers dismissed the theory that diet alone would be responsible for the convergence of physical appearance and instead support the theory of emotional efference.

Major histocompatibility complex
Major histocompatibility complex (MHC) is found in all jawed vertebrate and contains genes that are believed to be responsible for mate preferences and immune system functioning (Lie, Simmons, & Rhodes, 2010). The peptides contain information about the persons immunity gained from pathogens and parasites (Lie et al., 2010). In the interest of strong offspring with a strong immune system and increased genetic diversity, it would be in the best interests for humans to mate with others that have opposing immune systems (Lie et al., 2010). According to Lie et al. (2010) preferences for MHC difference in mating preference has been found in a range of animals and in the case of human clinical studies female preference for the odor of MHC-dissimilar males was found by (Wedekind and Furi, 1997; Wedekind et al., 1995) but not in two larger studies (Roberts et al., 2008; Thornhill et al., 2003). In the study conducted by Lie et al. (2010) it was found both men and women prefer partners with different MHC immunities to themselves however, men were able to detect through faces and women through body odour. This may also support the hypothesis and research that says men look more at physical attractiveness than women (Stroebe et al., 1971).

Relationship with parents
Wisezewska, Pawlowski, and Boothroyd (2007) conducted a follow up study to Bereczkei, Gyuris & Weisfeld (2004) who found positive parent-child relationships were associated with higher similarity between opposite sex parents and partners, this included for adopted children. The follow up study aimed to control for problems in the earlier study by using an anthropologist to measure facial dimensions, instead of basing resemblance things such as eye and hair colour. Results showed overall there to be no correlation between fathers faces and faces that female participants found most attractive however, women who rated their relationship with their father most highly picked faces that central features and face shape with their father.

Watkins, DeBruine, Smith, Jones, Vukovic, and Fraccaro (2011) explored the relationship between women's emotional closeness to their parents and their preferences for self-resembling faces in order to determine if sexual imprinting (familiarisation) of parents contributes to preferences for self-resemblance (Watkins, DeBruine, Smith, Jones, Vukovic, & Fraccaro, 2011). Results showed preference for self-resemblance in same-sex faces to be higher than opposite sex faces however, women's emotional closeness to their father was positively correlated with preference for self-resemblance in opposite-sex but not same-sex faces. These findings suggest preference for certain traits in opposite sex individuals are specific to traits possessed by the opposite-sex parent (Watkins et al., 2011).

A very unfortunate schema that may be learn't from parents is that of sexual and or violent revictimisation. A review of empirical literature in this area by Classen, Palesh, and Aggarwal (2005) shows that approximately 66% of children who are abused go on to be victimised again in adulthood. Moreover, a higher percentage of children who receive the abuse in a home environment by parents or caregivers go on to be victims of similar domestic violence later (Classen et al., 2005). This kind of research and understand is important to the wider community to help break these cycles of victimisation. On an individual level the victim is able to realise they are at a higher change of being victimised later in life and are able to learn and implement mechanisms to avoid this reoccurrence. From a clinical perspective, the professional can establish some background childhood information about the adult to help them understand why the end up in relationships where they become the vicim again. Conversely, they can re-educate young people who have been abused about what is/isn't appropriate in adult relationships to prevent the chances of revictimisation.

Sexual imprinting (familiarisation)
Sexual imprinting through parental familiarisation may be an alternative to the genetic based phenotype recognition theories. Sexual imprinting is the process whereby children acquire mate choice criteria through specific developmental processes from social contact with their parents (Bereczkei, Gyuris, Koves & Bernath, 2002).

In a study conducted by Bereczkei et al. participants were asked to view photographs of unknown people and match husband with wife and wife to husbands mother, before matching the relationships they were asked to rank the photographs on who looked most like the husband/mother in law and who looked least like. Results found wives were selected to be more similar to both their husbands and their mother-in-law compared to selection by chance, wives also showed significantly more resemblance to their mother-in-laws than their husbands and mothers who had a poor relationship with their sons or, who had rejected them were perceived as being less-similar to their daughter-in-law than those who had a good relationship with their sons (Bereczkei et al., 2002). Bereczkei et al. go on to argue that men don't simple 'match' desired similar phenotypic traits with potential mates, as genetic similarity theory suggests but that they create an image based on their mother's physical appearance and behaviour and create a schema and search for a partner who fits it. There is a possibility not explored by the researchers that this type of imprinting is an adaptive feature of genetic similarity theory, providing people with an easy to detect 'schema' from their opposite sex parent for partners who share similar genes.

In a study conducted by Little et al. (2003) they examined the relationship imprinting in humans based on partners and opposite-sex parents hair and eye colour. Their results found that assortative mating appears to be more influenced by parents traits than by self-similar traits. The study also found opposite sex parents hair colour was the strongest predictor for male partners hair colour and opposite sex parent eye colour as the single best predictor for both female and male partner selection.

Furthermore, Cate, Verzijden and Etman (2006) examined sexual preferences for exaggerated parental traits. Using zebras, they paired the preference for exaggerated phenotypes on being absent during a crucial time of imprinting learning. More study with a human population in this area would be preferential.

Short term v long term
Do we prefer the same kind of mates for short term flings as we do for marriage or long term commitment? Research suggests we don't. Research by Li and Kenrick (2006) found that both men and women look mainly at physical attractiveness when searching for a short term mate. Interestingly, women's threshold for an acceptable short term partner was considerably higher than male participants (Li & Kenrick, 2006). The answer for this high threshold from the woman's perspective may be that of potential reputation loss in a society that widely accepts men as having multiple partners and demonises women who do. According to Li and Kenrick (2006), when asked about what they consider before a one-night stand women answered that social norms of sexual restraint was important for them while men answered that social norms of sexual autonomy influenced their decision. Conversely, when asked to prioritise what was important in a mate, women rated status and resources and men rated physical attractiveness as their highest (Li & Kenrick, 2006).

Some of these differences had been explored in a study by Stroebe et al. (1971) whereby they looked at the interaction of physical attractiveness and similarity against dating, liking and marrying. They found there was no differences of similarity for dating and marrying however, liking was effected considerably more by similarity than dating (Stroebe et al., 1971). Consistent with the study by Li and Kenrick (2006) it was found that physical attractiveness had a larger effect on dating than on marrying or liking. The study, being published in 1971 does have some limitations mostly due to the inferences that are needed to be made in relation to the conservative language (Stroebe et al., 1971). It would be fair to assume 'dating' could be compared to short term relationships, flings or maybe even one night stands. Marrying could be compared to long term or committed relationship research and liking is somewhere in the middle, there is more emotional investment than one night stands or dating but, perhaps the length of relationship isn't there.

Conclusion
There was no accessible research on how the motivations for partners has changed over time. Prior to DNA testing and freely available immunisations, strategies such as explained by the paternity uncertainty hypothesis and MHC respectively would have been more crucial to survival. An extension of these scientific advances can also be noted in social change. Women have a higher threshold for one night stands compared to men, this was explained by the women as being a social expectation. Research on how this has changed over time would be beneficial.

A limitation of these theories includes a lack of an explanation of interracial attractiveness. A study by Bereczkei et al. (2004) does mention that children born to interracial parents do largely grow up to preference the race of the opposite sex parent however, how their parents came to partnership isn't explored (as cited in Wisezewksa et al., 2007). More research in this area would be advantageous, in a widely tolerant society such as Australia these types of relationships are common thus, supporting the idea that mate selection changes over time to adapt.

Psychology is becoming an interest to many with information becoming more widely available. For most, knowledge in this area is about questions such as 'why do my ex's all look the same?' or 'why do my partners always look like my dad?'. For professionals in psychology dealing with victims of domestic violence it may be about understanding revictimisation as a result of poor relationship schemas learnt from their parents.

It would be a hope that after reading this chapter the reader can see some of their own motives and reasons behind the people they have been attracted to.

If you or somebody you know is a victim of violence, please reach out and get help.