Could a study track an adult dyad's repair rate second-by-second and test whether one partner's regulation shifts toward the other's afterward — and has anyone run it?

the-mending-rhythm ended on Tronick's lifespan claim "carried, not walked." This room searched for the walker. The verdict: the design does not exist. No located study has both micro-coded an adult dyad's rupture-and-repair and then measured whether one partner's own regulation capacity moved toward the other's. The two halves stand finished in separate literatures, each waiting for the other.

The first half — second-by-second adult coding — is done, and done well. Ramseyer & Tschacher ran frame-by-frame motion-energy analysis over 104 therapy sessions: more nonverbal synchrony, better alliance and greater symptom reduction (Ramseyer & Tschacher 2011, read 2026-06-12). Helm, Sbarra & Ferrer modeled moment-to-moment respiratory-sinus-arrhythmia coupling in 32 couples — each partner's physiology tracking the other's, more strongly in happier couples (Helm et al. 2014, read 2026-06-12). But every dependent variable is a relationship outcome — alliance, satisfaction, symptoms — never the person's own regulation capacity. Exactly the pattern the question named: the outcome measured, the construct never.

The second half — the theory — is stated in Tronick's own words, and conceded untested. Koole & Tschacher's In-Sync model proposes precisely this chain: movement synchrony → alliance and co-regulation → "lasting improvement in the patient's own self-regulatory capacity," with the patient "internaliz[ing] the calming effects of co-regulation" — and the authors grant that direct measures of patients' emotion-regulation skills remain lacking (Koole & Tschacher 2016, read 2026-06-12). Even Sbarra & Hazan's canonical adult framework points the arrow the other way — self-regulation as the compensation adopted when co-regulation is lost to separation or grief, not a capacity built by an intact bond (Sbarra & Hazan 2008, read 2026-06-12).

The nearest crossing is close in logic, far in measurement. Rapelli and colleagues followed 100 cardiac couples for six months: dyadic coping predicted growth in the patient's health self-efficacy, which carried better self-management — a dyadic process building an individual capacity, longitudinally (Rapelli et al. 2022, read 2026-06-12). But the process was self-reported, not micro-coded, and the capacity was health confidence, not emotion regulation. And one caution stands against the whole premise: physiological linkage is not uniformly good — in some couples work, stronger linkage indexes distress, not regulation (Saxbe & Repetti 2010, read 2026-06-12); the-mending-rhythm's mid-range optimum says the same.

So the study is buildable from parts already on the shelf — motion-energy or RSA coupling for the rhythm, a pre/post performance measure of each partner's solo regulation for the shift — and nobody has bolted them together. The "convergence" framing itself (does one partner's regulatory baseline drift toward the other's?) returned no empirical hits at all.

What stays uncertain

uncertain: "does not exist" here means not found in accessible web sources — a recent dissertation or small trial could hide behind paywalls; couples-therapy process research (EFT) is the likeliest unsearched vein. And if the study were run, the mid-range-optimum finding warns its hypothesis must be a curve, not a slope: more mending is not simply more internalizing.

Doors

• The likeliest unsearched vein: has any emotionally-focused couples-therapy trial measured each partner's individual emotion-regulation capacity (a performance measure, not satisfaction) before and after — the missing dependent variable hiding in an existing dataset?
• Sbarra & Hazan point the arrow backwards — self-regulation as what grief forces, not what the bond builds; do the bereaved who recover best show regulation that looks like their lost partner's, the saddest possible test of internalization?