Self-expansion model

The self-expansion model of interpersonal relationships proposes that people have a basic motivation to expand their physical influence, cognitive complexity, social or bodily identity, and self-awareness, and that the psychological reward from falling in love or an intimate relationship is whatever creates this "expansion of the self".

Relationships are an important area for self-expansion, via a process called inclusion of the other in the self (abbreviated IOS), where aspects of a partner (e.g. traits, skills, attitudes, resources, abilities, and worldviews) are incorporated into one's own self concept. Self-expansion can also take the form of having new and exciting experiences with a partner.

Besides romantic love, opportunities for self-expansion include learning, career, family, friendship, athletics, travel, artistic expression, politics, gossip, religion, and the experience of nature.

The model was developed in the 1980s by the psychologists Arthur Aron and Elaine Aron, as a variant of the reward theory of attraction developed by interpersonal attraction researchers of the 1960s and 1970s. A robust research literature on self-expansion has grown, supporting the idea that people do in fact self-expand by absorbing others into their self-concepts, and that self-expansion contributes to relationship well-being. However, some other features of the Arons' original theory remain untested.