In psychology, the theory of attachment can be applied to adult relationships including friendships, emotional affairs, adult romantic and carnal relationships, and, in some cases, relationships with inanimate objects ("transitional objects"). Attachment theory, initially studied in the 1960s and 1970s primarily in the context of children and parents, was extended to adult relationships in the late 1980s. The working models of children found in Bowlby's attachment theory form a pattern of interaction likely to continue influencing adult relationships. Investigators have explored the organization and the stability of mental working models that underlie these attachment styles. They have also explored how attachment impacts relationship outcomes and how attachment functions in relationship dynamics. Mary Ainsworth and John Bowlby founded modern attachment theory on studies of children and their caregivers. Children and caregivers remained the primary focus of attachment theory for many years. In the 1980s, Sue Johnson began using attachment theory in adult therapy. Cindy Hazan and Phillip Shaver furthered research in attachment theory on adult relationships. Hazan and Shaver noticed that interactions between adults were similar to interactions between children and caregivers. For example, romantic or platonic partners desire to be close to one another, similar to how children desire to be close to their caregivers. Adults feel comforted when their attachments are present and anxious or lonely when they are absent. Romantic relationships, for example, serve as a secure base that helps people face the surprises, opportunities, and challenges life presents. Similarities such as these led Hazan and Shaver to extend attachment theory to adult relationships. Relationships between adults differ in many ways from relationships between children and caregivers. The claim is not that these two kinds of relationships are identical, but rather that the core principles of attachment theory apply to both child-caregiver relationships and adult relationships.