One-second exteroceptive self-anchoring as an acute-stress intervention: a dual closed-loop, anterior-insula hypothesis

Acute stress degrades prefrontal function within seconds, so interventions that must be retrieved and deliberately initiated — paced breathing, reappraisal, mindfulness — are least available at the moment they are needed. We hypothesize that a brief exteroceptive manoeuvre can re-anchor self-regulation without deliberate control. Specifically: (i) when a person views, for about one second and with relaxed focus, the space beside their own ears in a mirror at roughly 3 m optical distance, exteroceptive self-location signals (dorsal visual stream, right temporoparietal junction) and interoceptive signals converge on the anterior insular cortex; (ii) this convergence raises the precision of the self-model in the sense of active inference, down-regulates amygdala-driven threat responding through salience-network switching, and shifts autonomic balance toward parasympathetic dominance, observable as an immediate rise in heart-rate variability; (iii) the resulting state behaves as a dynamical attractor, so that recovery after a further stressor is faster and more complete in the mirror condition than in matched controls. Each component rests on established findings, but the causal chain as a whole has not been demonstrated, and a four-participant case series offers only fragmentary support. We therefore specify a factorial design (self-image × viewing mode × optical distance, with self-recognition and accommodation controls) and state, for each component, the outcome that would falsify it. If confirmed, the hypothesis yields a training-free, one-second intervention for acute stress; if refuted, it separates the contribution of self-image anchoring from that of accommodation release.