Abstract

This article explores the development of a rat model of mother-infant relationships from its origins in the psychosomatic investigations of the mid-1960s to its elaboration into a theoretical system in neurobiology. I reconstruct the research trajectory of a group of neurobiologists in the United States, with a focus on the experimental practices they adopted while building this animal model. Providing a microhistory of this decade-long undertaking, I show that what drove the development of the model in practice was a serendipitous finding about infants’ response to maternal separation. Detected inadvertently, the pup’s separation response acquired an epistemic significance of its own and reoriented the experimental system towards unanticipated paths. To explain this intriguing phenomenon, the neurobiologists kept on refining their material manipulations and stabilizing their experimental outcomes. They thus established a series of causal relationships that connected dysregulations of the infant’s physiological systems to disruptions in maternal care. As important as this interactive stabilization of technique and objects in the laboratory was how the researchers theorized the network of relationships derived from this technically constituted objectivity. Highlighting the practice-driven aspects of model-building, I demonstrate that what facilitated this theoretical process was an integrated design of complementary experiments. The outcome of each separate experiment of the research program came to bear upon the outcomes of other experiments, informing the development of future manipulations. It was this strategically driven integration process that allowed the experimenters to build expanding networks of causal relationships and consolidate them into a neurobiological theory.