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Self expansion model

Author: Dr Simon Moss


The self-expansion model assumes that individuals ultimately form relationships to facilitate growth and progress (see A. Aron & E. N. Aron, 1986; A. Aron, Norman, E. N. Aron, McKenna, & Heyman, 2000; E. N. Aron & A. Aron, 1996). This theory can explain some key observations, such as the finding that engaging in creative and challenging activity together, of reflecting upon events that provoked shared laughter (Fraley & Aron, 2004), improve satisfaction in relationships.

Description of the model

According to the self-expansion model, the yearning to grow and expand is key motivation in humans (A. Aron & E. N. Aron, 1986). That is, as a consequence of this motivation, individuals inherently enjoy novel, exciting, and challenging activities, which promote this growth and expansion.

One of the key sources of growth and expansion derives from romantic relationships (A. Aron & E. N. Aron, 1986). That is, when individuals form a romantic relationship, their own sense of self assimilates some of the qualities and characteristics of their partner. If their partner, for example, is mathematical, the individuals themselves feel their self encompasses this attribute.

Thus, romantic relationships, especially with someone who is different to the self (Aron & Aron, 1997), can fulfill this desire to grow and expand. As a consequence, individuals experience the positive affect, and feelings of flow and absorption (Graham, 2008) that such growth and expansion evoke. Individuals begin to associate these positive affective states with the relationship. Over time, as a consequence of this association, they perceive the relationship more positively. That is, they attribute their positive affective states to the relationship (A. Aron, Norman, E. N. Aron, McKenna, & Heyman, 2000; Aron, Aron, Tudor, & Nelson, 1991).

Hence, according to this account, love emanates from this desire to grow and expand (E. N. Aron & A. Aron, 1996). That is, love motivates the formation and maintenance of romantic relationships.

Determinants of relationship satisfaction

Initially, many relationships are fulfilling, because partners can readily engage in novel and challenging activities to satisfy their desire to grow and expand. As the relationship progresses, however, fewer opportunities to engage in novel and challenging experiences are available. Self expansion might stall, feelings of boredom rather than positive affect might surface, and relationship satisfaction might decline (A. Aron, Norman, E. N. Aron, McKenna, & Heyman, 2000).

Instead, to maintain solid relationships, couples must identify more opportunities to engage in inspiring, exciting, and novel activities together. Couples who can uncover such opportunities will tend to maintain a flourishing and satisfying relationship (E. N. Aron & A. Aron, 1996).

Empirical evidence

Inclusion of partner in the self

According to the self-expansion model, individuals tend to assimilate the traits and characteristics of the partner into their conceptualization of themselves. A variety of studies have confirmed this hypothesis (Aron, A., Aron, E. N., Tudor, & Nelson, 1991; Mashek, Aron, & Boncimino, 2003; Smith, Coats, & Walling, 1999).

Some of these studies examine allocation of resources. Participants were asked to allocate money to themselves, a best friend, and another person. In some conditions, participants were informed that nobody would know if they received this money or not. Typically, participants would allocate money to themselves and their best friend to a similar extent& they would not allocate money to other individuals, like stranger or acquaintances, for example (see Aron, Aron, Tudor, & Nelson, 1991)

A second set of studies show that memory advantages for words that relate to the self also apply to terms that relate to romantic partners or close friends. That is, usually individuals can more readily memorize a list words, such as adjectives, if they apply to themselves. Nevertheless, they can also memorize words that apply to someone who is close to them (for a meta-analysis, see Symons & Johnson, 1997)

A third set of studies indicates that individuals confuse traits that represent themselves with traits that represent their partners (e.g., Aron, Aron, Tudor, & Nelson, 1991). In a typical study, participants must decide whether or not various adjectives or traits describe themselves. Reaction times are protracted when the traits correspond to their partner but not themselves.

Measure of inclusion

Aron, Aron, and Smollan (1992) also developed a procedure to assess the extent to which individuals feel they have incorporated their partner into their conceptualization of themselves. Several pairs of circles are presented, each with varying levels of overlap, ranging from no overlap to complete overlap. Participants specify the pair of circles to represent the extent to which they feel their partner is included in their sense of self. This measure predicts marital satisfaction as well as relationship maintenance over the next three months.

This scale can also be used to represent overlap between the self and some social collective, such as the community (e.g., Mashek, Cannaday, & Tangney, 2007). A continuous version of this scale has also been developed, which ranges from 0 to 100, using a computer (see Le, Moss, & Mashek, 2007)

Impediments to novel activities

According to the self-expansion model, relationships that impede growth and expansion should be experienced as unsatisfying. Indeed, Lewandowski and Bizzoco (2007) showed that individuals experience more positive moods after a dissatisfying relationship dissolves. When individuals dissolve such obstructive relationships, their mood improves and they are also less likely to endorse items such as "I feel as though many of my good qualities have been lost" and "I do not feel like myself anymore". Hence, any loss of self tends to be reversed.

Preference for similarity

The self-expansion model also implies that individuals will often value traits in their partner that differ from their own characteristics. Such traits enable these individuals to expand their conceptualization of themselves.

Aron, Steele, Kashdan, and Perez (2006) corroborated this proposition. They demonstrated the usual inclination of individuals to prefer strangers who are similar to themselves. However, if told they might be able to form a relationship with this stranger in the future, this preference of similarity diminished significantly.

Simialrly, Amodio and Showers (2005) showed that couples who are dissimilar to each other are more more satisfied with their relationship. Interestingly, the benefits of dissimilarity decline when individuals are committed to each other. Presumably, commitment may curb the motives to expand the self.

Antecedents to self expansion

Engaging in novel activities with a partner

The self-expansion model also implies that couples who engage in exciting activities together-experiences that will facilitate growth-will experience relationship satisfaction and passionate love. Again, this proposition has been confirmed in several studies (A. Aron, Norman, E. N. Aron, McKenna, & Heyman, 2000).

In some of these studies, however, these exciting activities were also physiologically arousing. Hence, excitement and arousal was confounded. To counter this issue, studies have shown that couples who engage in exciting, but not arousing, tasks also experience relationship satisfaction and passionate love (Lewandowski & A. Aron, 2004).

More specifically, Graham (2008) applied the experience sampling method to examine whether momentary engagement in exciting activities together corresponds to changes in relationships satisfaction. Consistent with the self-expansion model, such activating and exciting experiences did coincide with perceived relationship quality.

Engaging in novel experiences alone

Research in the literature on self-expansion theory has shown that partners who share novel experiences experience a sense of self-expansion, and these feelings project onto the relationship, improving marital satisfaction. Recent studies have shown that novel experiences alone can also promote this sense of self-expansion (Mattingly & Lewandowski, 2014).

In one study, participants completed a measure that assesses the degree to which they had engaged in a range of 49 experiences, such as extended their knowledge, learned a skill, became interested in a new ideology, and so forth. In addition, they completed a measure that assesses the breadth of their self-concept& they indicated which of various traits, such as happy, independent, selfish, caring, anxious, and smart, they exhibit. Engagement in novel experiences was positively associated with the breadth of self-concept.

The second study replicated this finding. In particular, as this study showed, the relationship between novel experiences and self-concept size persisted even after controlling the number of items they believed belonged in an effective kitchen. The results, therefore, cannot be ascribed to an acquiescence or effort bias.

The third study manipulated exposure to novel experiences using embodied cognition. In this study, a variety of bricks were assembled. On each brick was a label that identified a novel experience, such as fly in a helicopter, learn how to juggle, and so forth. Participants identified three experiences they perceived as novel and interesting or neither novel nor interesting. Participants were then granted an opportunity to pull these bricks towards themselves or to point at these bricks. Relative to the other conditions, if participants pulled bricks towards themselves that represented novel experiences, they reported a broader self-concept.

Self concept clarity

As Lewandowski, Nardone, and Raines (2010) showed, when individuals are certain of their qualities and attributes, called self concept clarity (see also optimal self esteem), they are more likely to feel a sense of overlap with their relationship partners. In one study, participants completed a series of measures. Specifically, self concept clarity, relationship satisfaction, relationship commitment, inclusion of others in the self, and self esteem were all measured. Self concept clarity was indeed associated with both satisfaction with relationships and commitment to romantic relationships. Furthermore, inclusion of others in the self, in which people feel their identity overlaps considerably with their partner, mediated these relationships.

Presumably, if self concept clarity is elevated, individuals are more certain of which qualities they have yet to acquire. They can, therefore, more readily determine which qualities in their partner they need as a means to complement these shortfalls. They can determine which attributes in their partner they would like to integrate with their own self concept. Nevertheless, because of their clarity, they are still cognizant of their own attributes, ensuring they maintain a sense of personal identity. Accordingly, they feel a stable connection to this person, enhancing relationship quality.

Consequences of self-expansion to individuals

Broader self-concepts, in which individuals feel they exhibit a range of traits, tend to offer many benefits. If people report an extensive self-concept, their self-esteem and self-efficacy to resolve problems increases, for example (Aron, Paris, & Aron, 1995).

Related concepts


Rather than depend on one relationship, such as a parent or partner, to derive emotional support, some people depend on several relationships, and each relationship overcomes a specific emotion. For example, people might depend on a sibling to feel uplifted while sad. They might, however, depend on another friend to sooth their anxiety. These distinct relationships are called emotion-ships (Cheung, Gardner, & Anderson, 2015).

For example, in one study, participants received a list of five instances in which they like to improve their emotions, such as the need to cheer up while sad, sooth their anxiety, diminish their anger, amplify their anger, and capitalize on their happiness. For each instance, participants indicated one friend who is effective, and one friend who is ineffective, in achieving each of these goals separately. Next, participants were induced to feel sadness, anxiety, or anger, before naming their friends in the order in which they sprung to mind as well as how valuable they regarded each friend. Participants were more inclined to name the friend first, and value the friend, that diminishes the emotion that was induced

More importantly, people who have developed distinct friendships to regulate each emotion tend to experience greater wellbeing, even after controlling relationship quality and various individual characteristics. That is, if people had developed friendships with various individuals who diminish only one specific emotion, they reported greater satisfaction with life. This relationship persisted after controlling attachment style, personality, and self-monitoring.

Presumably, if people can develop on distinct individuals to regulate different emotions, they can utilize the strengths of their friends better. Some friends may help them override sadness but not anxiety, for example. No one friend is likely to be effective in all circumstances.


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Last Update: 6/19/2016