In contemporary music and arts practices the previously distinct roles of author, composer and performer have become increasingly conflated, catalysed by the use of computer technology. Newly combined roles of composer and performer that are assumed by one or more people or computer systems are identified and described, as well as actions including preparation, organisation and presentation. In this paper the interface is described as an ‘interactivated space’ to encompass both the intimate scale of a performer manipulating the materials through an on-body interface, and the larger in-space interface where the work is shared with the performers and audience. Two examples of projects the authors are involved in are described, which form the basis for further discussion. The two interfaces that manifest themselves in the processes, the instrument and the score are discussed in more detail with a focus on their changed appearance and role.