People with personality disorders (PDs) are often difficult to reach emotionally in therapy. As music therapy (MT) provides an entry point to emotions and facilitates contact and communication, it is regularly used with this target group. This study presents a case study of a 40-year-old woman diagnosed with a PD not otherwise defined. \"Nina\" experienced depressive and physical symptoms, including severe anxiety. Previous treatments had failed. In MT, she experienced a sense of safety. Over the course of the treatment, she experimented with making herself heard, learned to listen to herself and recognize her own physical signals, permitted closeness and cooperation, and began setting boundaries and taking initiative. She got in touch with and learned to regulate emotions such as sadness and fear. Self-criticism gave way to a more compassionate self. Nina began to experience positive feelings and showed progress in her work and social interactions. The findings suggest that MT can directly connect to clients\' emotions, behaviors, and thoughts in a way they perceive as safe. This is of the utmost importance for clients who are hard to reach. The use of MT can potentially prevent dropout and further entrapment in personality problems.

Classical theories of intersubjectivity hold that the first interactions in which children participate are dyadic (adult-baby). However, thanks to the material shift that is taking place in the cognitive sciences, an increasing number of authors began to recognise the constitutive role that materiality has for cognition, from the very beginning of life. Interactions do not occur in a vacuum, but within a meaning-loaded material world that adults actively seek to bring to children. While in the field of dyadic interactions studies on communicative musicality have shown how interactive exchanges are structured and how that structure unfolds over time, little is known yet about the internal structure of early triadic interactions. In this paper, we propose a longitudinal, mixed and multilevel methodological framework aimed at describing the dynamics of the musical organisation of early triadic interactions between adults, babies and things, and its development over different timescales. We conclude that if researchers want to fully understand early triadic interactions and their musical structuring, further studies that take into account the cognitive relevance of things and the dynamics of our interactions with and through materiality are needed.