This article is an account of the dynamics of interaction across the social sciences and neurosciences. Against an arid rhetoric of ‘interdisciplinarity’, it calls for a more expansive imaginary of what experiment – as practice and ethos – might offer in this space. Arguing that opportunities for collaboration between social scientists and neuroscientists need to be taken seriously, the article situates itself against existing conceptualizations of these dynamics, grouping them under three rubrics: ‘critique’, ‘ebullience’ and ‘interaction’. Despite their differences, each insists on a distinction between sociocultural and neurobiological knowledge, or does not show how a more entangled field might be realized. The article links this absence to the ‘regime of the inter-’, an ethic of interdisciplinarity that guides interaction between disciplines on the understanding of their pre-existing separateness. The argument of the paper is thus twofold: (1) that, contra the ‘regime of the inter-’, it is no longer practicable to maintain a hygienic separation between sociocultural webs and neurobiological architecture; (2) that the cognitive neuroscientific experiment, as a space of epistemological and ontological excess, offers an opportunity to researchers, from all disciplines, to explore and register this realization.