The integration of neuroscience and psychotherapy research has long been a topic of interest in the field of mental health. A significant challenge in psychotherapy research is understanding the dyadic interaction between patient and therapist. This interaction is complex, emerging from a myriad of multi-level factors such as gestures, verbal communication, mentalization, and environmental influences. This article aims to present a roadmap for the future integration of neuroscience and psychotherapy research, addressing the complexities of human interaction. We introduce the 4E/MoBI approach, a framework that combines theoretical and methodological tools to study the dynamics of the brain, body, and environment in real-world settings. This approach emphasizes the use of physiological systems (e.g., heart and brain), behavioral interactions (e.g., conversations and eye-tracking), and environmental video recordings. Additionally, the scalable experimental design (SED) heuristic is discussed as a method to blend controlled experiments with real-world scenarios, allowing for the parametric testing of neurobehavioral markers. As a practical demonstration of the SED heuristic within the 4E/MoBI framework, a concrete experimental example using the N170 event-related potential (ERP) component is presented. While the N170 ERP component is not posited as the foundational marker in the field, it serves to illustrate the application of hypothesis-driven designs and analyses. The 4E/MoBI approach offers a promising avenue for the integration of neuroscience and psychotherapy research. By addressing existing gaps, such as the physiology and phenomenology of expertise in psychotherapy, this framework can foster a virtuous relationship between the two disciplines, paving the way for more comprehensive and nuanced understandings of therapeutic interactions.