The theory called continuing bonds
A relationship changing shape, not a relationship ending.
For a long stretch of the twentieth century, the dominant model of grief in Western psychology held that healthy mourning ended in detachment: the bereaved person's task was to withdraw emotional attachment from the person who died and, eventually, redirect it elsewhere. Grieving well meant, more or less, letting go. A person who kept talking to a dead spouse years later, who set a place at the table out of habit, who still asked a dead parent's opinion in their head, could be read under that model as failing to finish the job.
What changed in 1996
In 1996, the researchers Dennis Klass, Phyllis Silverman, and Steven Nickman published a book arguing against that model directly. They proposed the term continuing bonds: the idea that maintaining an ongoing, evolving relationship with someone who has died is not a failure of grief, but is, for many people, what healthy grief actually looks like. The bond does not need to be severed. It changes form instead, and that change is the work, not a detour from it.
The shift was not a claim that every bereaved person must keep such a bond, or that detachment is wrong for everyone. It was a challenge to treating detachment as the only correct endpoint, and to pathologizing the people who never arrived there.
What it looks like in practice
Continuing bonds shows up in ordinary, unremarkable ways more often than dramatic ones. Keeping an object. Visiting a grave. Talking to someone out loud, in a car, at a sink, into a disconnected phone. Asking, internally, what a dead parent would think of a decision. None of these count as symptoms of unresolved grief under this model. They are closer to what resolved grief tends to look like, for the people who find their way there.
The theory does not say a bond has to look any particular way, or last any particular length of time, or feel the same at year one as it does at year ten. It only says that ending the relationship is not the goal, and that people who keep one going are not doing grief incorrectly.
Why a Wind Phone fits the idea
A Wind Phone was not built with this theory in mind. Itaru Sasaki was not working from a textbook when he put a disconnected rotary phone in his Ōtsuchi garden. He was trying to keep talking to his cousin. But the object he built turned out to be an almost literal version of what continuing bonds describes: a way to keep the relationship active, out loud, without pretending the person is still alive to answer. Whether this kind of talking is normal is really the same question continuing bonds was written to answer, decades before anyone built a phone for it.
Say what you need to say. The line is connected to nothing: no one hears you, nothing is recorded, nothing is stored.