Nicolás Andrés Hinrichs

In The Brain Abstracted, Mazviita Chirimuuta calls for vigilant awareness of how neuroscientists simplify complex realities, warning that every explanatory gain from abstraction comes at the cost of potential distortion. In this paper, I apply and extend Chirimuuta’s framework by considering the case of hyperscanning in psychotherapy, i.e., the simultaneous recording of the therapist’s and patient’s brain activity. This application demonstrates three points about the simplification of inter-brain synchrony in social neuroscience: (i) the issue of scale mismatch; (ii) the risk of “metric-as-mechanism”; and (iii) the necessity of capturing interaction dynamics. By instituting three corresponding “guardrails”, namely, (i) triangulating neural data with behavior and experience, (ii) modeling bidirectional influence with lag-sensitive methods, and (iii) bridging momentary neural events to the arc of the whole session, hyperscanning research can avoid the slide into what Chirimuuta terms “formal idealism” and remain anchored to manipulable clinical reality. I further propose that inter-brain synchrony should be regarded as a practical phenomenon in the psychiatric sense, what Haslam calls a “practical kind,” valued for its utility in guiding interventions rather than as a natural mechanism of empathy. Hyperscanning in psychotherapy thus both confirms Chirimuuta’s warning about the costs of constructive simplification and motivates an extension of her framework to cover the special case of two brains in intimate interaction.

Second-person neuroscience holds social cognition as embodied meaning co-regulation through reciprocal interaction, modeled here as coupled active inference with affect emerging as inference over identity-relevant surprise. Each agent maintains a self-model that tracks violations in its predictive coherence while recursively modeling the other. Valence is computed from self-model prediction error, weighted by self-relevance, and modulated by prior affective states and by what we term temporal aiming, which captures affective appraisal over time. This accommodates shifts in the self-other boundary, allowing affect to emerge at individual and dyadic levels. We propose a novel method termed geometric hyperscanning, based on the Forman-Ricci curvature, to empirically operationalize these processes: it tracks topological reconfigurations in inter-brain networks, with its entro-py serving as a proxy for affective phase transitions such as rupture, co-regulation, and re-attunement.