Bodily Mediation: self-other dynamics in adults and fetuses

Human beings are inherently social, with a sense of self deeply connected to the capacity for social attunement—a process of aligning behaviors, emotions, and physiological states with others, fostering shared understanding and connection. This alignment is facilitated by bodily mediation, where the body actively engages with the environment and others. Behavioral contagion (e.g., yawning, itching) and body ownership illusions (e.g., the Rubber Hand Illusion) demonstrate the fluidity of boundaries between self and other, supported by neural systems that enhance social resonance. The foundations of bodily mediation trace back to prenatal development, where the fetus, through co-embodiment with the mother, begins to form bodily self-awareness, laying the groundwork for future social attunement. This dissertation examines bodily mediation's influence on self-other relationships across the lifespan, bridging early prenatal development and adult social interactions. In adults, it investigates how the temporal binding window (TBW), a measure of multisensory integration, affects the flexibility of self-other boundaries. It is hypothesized that wider TBWs correlate with a more permeable self-other distinction, resulting in heightened social attunement. Results from the first study (N = 50) indicate that participants with wider TBWs exhibit increased susceptibility to body illusions and contagious behaviors. Building on these findings, the second study investigates the plasticity of TBW through a training protocol aimed at TBW narrowing. In a sample of 30 participants, first session measurements were taken in social contagion, RHI, and simultaneity judgment tasks, followed by TBW-narrowing training and second session measurements. Post-training results indicate a reduction in embodiment and contagion susceptibility, supporting the hypothesis that a narrower TBW stabilizes self-other boundaries, thus reducing automatic mimicry responses. The third study focuses on motor resonance between mother and fetus, examining whether maternal yawning elicits fetal yawns, as observed through 2D ultrasound in 33 mother-fetus dyads. A significant increase in fetal yawning following maternal yawns suggests that motor resonance and attunement begin prenatally, forming the basis for later social and motor coordination. Additionally, a neural network model analyzed maternal and fetal yawning kinematics, providing further insights into early motor synchronization. Collectively, these studies provide a comprehensive view of how bodily mediation, through mechanisms of multisensory integration, body ownership, and motor resonance, facilitates social attunement from prenatal stages through adulthood. This research underscores bodily mediation as a core component of social connection, shaping self-other boundaries and fostering relational attunement across life stages.