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The self-expansion model is based on two key principles. The first is that humans have a primary motivation to self expand. The second principle is that individuals often achieve self-expansion through close relationships which allow the inclusion of the other in the self.
One of the underlying themes of self-expansion is that individuals have a very basic motive to self-expand. Self-expansion is the desire to enhance an individual's potential efficacy. Motivational models often refer to self-efficacy as one's belief that they are competent and can achieve specific goals. However, within the self-expansion model, potential efficacy is used instead, as it only refers to obtaining resources that will make goal attainment possible. Achievement of this goal is a secondary concern. According to the self-expansion model, people increase potential efficacy by creating close relationships, which in turn, increases material and social resources, perspectives, and identities. Some examples of resources include the following: social support, possessions, information, and friendship networks. Perspectives are the way people appreciate the world and ascribe causal explanations for people's behaviors. Identities refer to a person's memories and characteristics. Self-expansion is not consciously motivated. A person does not explicitly attempt to be part of a close relationship for the sole intention of increasing physical and psychological resources.
However, the motivation to self-expand still does influence attraction to others for a potential close relationship. Aron and Aron suggest that our attraction is broken down into two components based on Rotter's value-expectancy approach. Desirability is the perceived total amount of self-expansion possible from a potential close relationship. The second factor, probability, refers to the likelihood that the close relationship with the individual can actually be formed. It can also be conceptualized as the likelihood that self-expansion will occur. Consequently, individuals will seek a partner that has high social status and a greater number of resources. However, to maximize self-expansion, consideration is also given to how likely this person will be loyal and desires to be in the close relationship.
Including the other in the self
The second principle of the self-expansion model is that people use close relationships to self expand by including the other in the self. The self is often described as the content or the knowledge of who we are. According to Aron and Aron, when entering a close relationship a person should perceive that the self and other should begin to overlap by including aspects of the other in the self. More specifically, when the other makes his or her resources available, this leads to the belief that these resources are now included in the self. These new resources lead to greater inclusion of the other in the self by also incorporating the other's perspectives and identities in the self.
Aron, Aron, Tudor and Nelson conducted several classic studies that scientifically demonstrated that we include the other in the self. In one experiment, participants were more likely to distribute money equally between the self and the close other in comparison to distributing the money between oneself and a stranger. The sharing of resources was suggestive of including the self in the other. In a second experiment, participants were more likely to remember more nouns for a stranger than a close other (one's mother). This supported the IOS phenomenon, as participants were more likely to take the perspective of the close other thus not being able to remember descriptive nouns of that person. In a final experiment participants were required to make yes/no decisions on whether certain traits belonged to themselves. Decisions on traits that were different between a participant and a close other had longer reaction times than decisions on traits that were different between a participant and a stranger. It was suggested that the increased confusion between the self and the close other was directly related to integrating the other in the self. The degree of closeness in the relationship affects the self and other reaction studies. As two individuals become closer, there is greater confusion and therefore a longer reaction time. As a result, as closeness of a relationship increases, there will be a greater inclusion of the other in the self.
Measuring inclusion of the other in the self
The Inclusion of the Other in the Self Scale (IOS Scale) is one of the most frequently used tools to assess this phenomenon. The scale consists of seven Venn diagram-like pairs of circles that vary on the level of overlap between the self and the other. Respondents are asked to select the pair of circles that best represents their current close relationship. Several studies have showed that this measurement tool is effective in getting accurate depictions of the amount of closeness and the inclusion of the other in the self. IOS has also been assessed with the Continuous IOS, a Java-based applet suitable for online surveys that measures IOS on a continuous scale from 0-100 Participants are instructed to use their mouse to move one of the circles (typically labeled "self") towards the other (typically labeled "other") until the degree of overlap best describes the relationship in question. The IOS Scale has also been adapted to measure inclusion in other contexts, for example community connectedness via the Inclusion of Community in the Self Scale. The adaptability of IOS is broad as demonstrated by recent versions substituting target with "X."
Inclusion of the ingroup in the self
The idea of including the other in the self has been extended to include an entire ingroup in the self. An ingroup is an interdependent set of individuals with which a person identifies. The individual believes he or she is a member of this group. In fact, several academic groups have found similar findings in the me/not me reaction time paradigm at a group level. Participants showed a slower reaction time for traits that were incongruent between the self and ingroup. This was in comparison to quicker reaction times for traits that were congruent between the self and ingroup. The slow reaction times were consistent with the inclusion of the ingroup in the self claim as it suggested that the individual had included group characteristics in the self. As a result, there was difficulty recalling if a trait belong to the self or ingroup. Several researchers have examined the role of ingroup identification (i.e. a person's prolonged psychological connection to an ingroup) and self-expansion. In fact, Trop and Wright refined the meaning of ingroup identification and believed it was analogous to the inclusion of the ingroup in the self. The authors found that the degree of connectedness to the ingroup will affect confusion of self-descriptors. People who highly identified with an ingroup showed slower reaction times for self-descriptors that did not relate to the ingroup (this is consistent with previous findings). However, low ingroup identification lead to no differences in reaction times between whether or not the self-descriptors were also descriptive of the ingroup. This demonstrated that the level of identification with an ingroup can be conceptualized as the degree to which we will include the ingroup in the self.
The central motivation for including the ingroup in the self parallels the self-expansion model at the interpersonal level. The self-expansion model suggests that we are strongly motivated to expand ourselves by including the other in the self. This occurs when an individual incorporates the other's perspectives, identities and resources. Likewise, it has been proposed that including an ingroup in the self, or ingroup identification, is partly influenced by the self-expansion motive. Inclusion of the ingroup's perspectives and resources can increase one's confidence in completing a variety of goals. Thus, a group's attractiveness is often based on the potential for self-expansion. A group with higher social status and a greater amount of potential resources is more likely to be included in the self.
Measurement of inclusion of the ingroup in the self
Tropp and Wright created an instrument to measure the extent that an individual includes the ingroup in the self. The Inclusion of the Ingroup in the Self Scale (ISS Scale) was based on the Inclusion of the Other in the Self Scale. Similar to the original scale, seven pairs of circles vary on the degree of overlap between the self and the particular ingroup. The scale has been well validated and the degree of inclusion of the ingroup in the self is said to capture the sense of ingroup identification.
Self-expansion, including the outgroup in the self, and intergroup relations
An abundance of research focuses on the negative interactions between different groups (e.g. negative attitudes, intolerance, discrimination). However, there is sparse evidence to explain the positive aspects of intergroup relations such as reduction of prejudice. The contact hypothesis(by Gordon Allport) is one area of psychology that focuses on positive aspects of intergroup relations. The hypothesis suggests that when there is cooperation, equal status, common goals and authority support then contact between members of different groups can result in reduced negative attitudes. In addition, positive emotions between intergroup members was said to be of utmost importance as it would lead to positive attitudes which, in turn, would generalize to the entire outgroup. An outgroup is set of individuals with which the individuals does not identify. It was unclear how this attitude generalization actually happened. Recently, the process of including the outgroup in the self was used as an explanatory mechanism for this generalization.
Including the outgroup in the self is based on the similar self-expansion notion of including the other or ingroup in the self. As a person becomes a friend with an outgroup member, the aspects of the outgroup is included in the self when that group is made salient. Essentially, representation of the outgroup and its identity is shared with our representation of the self. Including the outgroup in the self can vary; a person may actually become a member of an outgroup. However, in certain circumstances this is virtually impossible and we simply psychologically identify with the group even though we are aware that we are not part of it. Upon inclusion of the outgroup in the self, we now give that group several benefits. These benefits include taking pride in the group, sharing resources, and positive biases in causal explanations of the group. These benefits all increase the likelihood for reduced outgroup prejudice, hence its use as a mechanism for the contact hypothesis.
It is important to note that the focus of the inclusion of the outgroup in the self is initially at the interpersonal level (i.e. between individuals). The interaction needs to have interpersonal closeness for inclusion of the self in the other to occur. Consequently, a decategorized approach to contact should be used where the focus is on personal identities instead of group identities. By focusing on personalization, there is a greater chance for the development of closeness. Eventually, group membership needs to become available so that an individual can now include the outgroup in the self as well. However, it is believed that group membership will become more central in a natural manner as the close relationship develops.
Empirical evidence seems to support the inclusion of the outgroup in the self hypothesis. In one study white women were paired off with either another white woman (ingroup member) or a Latina woman (outgroup member). The pairs of women met over an extended period of time completing different activities together, which led to a measurable close friendship. Women with an intergroup friendship were more likely to have positive intergroup attitudes, less likely to endorse anti-minority policies and less likely to demonstrate intergroup anxiety. The study suggests that the intergroup close relationship led to improved attitudes towards the entire outgroup as suggested by the inclusion of the outgroup in the self mechanism. Another study also found that the level of inclusion of the outgroup in the self would affect the amount of decreased prejudicial attitudes. Further, simply including a friend in the self who has a close relationship with an outgroup member can decrease outgroup prejudiced attitudes. Knowing that a friend includes an outgroup member in the self allows for the individual to include that entire outgroup in the self. In turn, this also leads to positive attitudes about the outgroup.
It may be the case that individuals want to make friends with outgroup members (instead of oppress and mistreat the outgroup) because of the self-expansion motive. Based on Aron and Aron's original work, people want to expand the self and an optimal way of doing so is to make close friendships that give the opportunity for increased perspectives, identities and resources. People who are most similar to ourselves provide a diminished capacity for self-expansion. As a result, an individual may turn to outgroup members for friendship because they are different from one's self-concept. These differences allow for a greater likelihood to increase resources, identities and perspectives, which is consistent with the self-expansion motive. A recent study has shown that, consistent with this idea, priming high self-expansion motivation enhances outgroup self-expansion and the quality and outcomes of outgroup interactions (e.g. greater self-efficacy, reported closeness, and self-growth).
Barriers to self-expansion at the intergroup level
Self-expansion motives can explain why people may appreciate intergroup contact, however, it can also provide explanations for why we avoid this intergroup contact. People may be cautious of self-expansion due to a sense of self-loss. As we self-expand in one area we may put ourselves at risk of losing aspects of the self in another area. Consequently, people may be fearful of creating a close relationship with an outgroup member as this may trigger animosity from original ingroup members. Often individuals must balance between potential benefits of including the outgroup in the self with the potential loss of ingroup friends and the associated resources. If the self-loss outweighs the self-expansion, it is possible for a decrease in perceived self-efficacy.
A second barrier for self-expansion is the notion for an overabundance of self-expansion in a short period of time. The accumulation of new resources and perspectives in our self-concept leads to a need for self-integration (i.e. combining different resources, identities and perspectives into single overarching self-concept). An excessive amount of self-expansion without proper self-integration can be quite stressful (e.g. moving to a new city, or starting a new job). It has been suggested that when a person is socially stable, self-expansion via an outgroup member is most likely to be successful. Consequently, the likelihood for cross-group contact and the inclusion of the outgroup in the self is dependent on the degree of self-expansion in other domains. Expansion = motivation and believing.
Self-expansion beyond relationships
More recently, self-expansion research has begun to shift away from investigating self-expansion in a social context (e.g. romantic relationships) and instead has focused on self-expansion processes and outcomes of self-expansion at the individual level. Research has also focused on self-expansion in domains such as the workplace. Results of these research studies has shown that self-expansion can (and does) occur at the individual level (e.g. through hobbies and spiritual experiences) and in workplace settings. Similar to findings from social self-expansion literature, individual self-expansion also has positive effects and includes the same processes (e.g. motivation, self-efficacy). Self-expansion has also been presented theoretically within a framework of self-concept change. That is, self-concept change can be thought of as occurring along two independent dimensions: valence (positive vs. negative content) and direction of change (increase vs. decrease in content) and self-expansion represents one of the four possible processes of self-concept change (increasing positive content).
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