selfexpansion

Self-expansion is the psychological process by which individuals enlarge their self-concept by incorporating new attributes, identities, experiences, and relationships. It is a central idea in the Self-Expansion Model, developed by Aron and Aron, which holds that people are motivated to extend their boundaries to gain new resources, perspectives, and efficacy.

A key mechanism of self-expansion is inclusion of other in the self (IOS), where close others are represented as overlapping with one’s own self. Through shared goals, joint activities, and partner traits, individuals come to see themselves as interdependent with others, expanding the domains that count as part of the self.

Self-expansion is associated with positive relationship outcomes, such as increased satisfaction, trust, and commitment. Engaging in novel, challenging experiences with a partner can foster growth in closeness, empathy, and positive affect. Over time, expansion may contribute to personal development, broadened preferences and values, and greater resilience.

Researchers measure self-expansion using scales like the Inclusion of Other in the Self Scale and the Self-Expansion Inventory, which assess perceived overlap and the breadth of expanding domains (roles, characteristics).

Critiques note that expansion is not universally beneficial; it can threaten autonomy if pursued excessively, and cultural variation in self-construal may influence its applicability. Some findings rely on correlational designs, limiting causal inferences.

See also: inclusion of Other in the Self; relationship psychology; self-concept.