The idea that adults love the way they were once attached to a caregiver isn't just a popular metaphor — it traces to specific, tested research, with real nuance worth understanding.

In 1987, Hazan and Shaver tested whether Ainsworth's infant attachment categories — secure, avoidant, anxious-ambivalent — could describe adult romantic experience. Their findings (56% secure, 24% avoidant, 20% anxious-ambivalent) closely matched Ainsworth's infant proportions. Later work added a fourth category and, more recently, the field has shifted toward understanding attachment as a spectrum rather than a rigid box.

This guide covers where the framework comes from, what "earned secure attachment" means, and how rigid these categories actually are.