The choice of what media and materials to use in the design of any specific narrative environment, as transmedial artefact, process or event, is led by the question posed by Ryan and Thon (2014: 3), who are parodying Seymour Chatman: what can medium x do in terms of storyworld creation or representation that medium y cannot, and vice versa? The choice of medium concerns what stories can be told, how they are told and why they are told. Thus, by shaping narrative, media shape human experience (Ryan, 2014: 25).
The term medium can be used in a semiotic sense, as the articulation of signs, or in a technological or cultural sense, such as film, theatre or art installations. One widespread trend in media studies is to associate media with specific technologies of communication, for example, writing, print, cinema, photography, television, radio and the telephone, with the uses of digital technology referred to as ‘new media’ (Ryan, 2014: 27).
Another approach is to list culturally recognised forms of communication, such as film, photography, literature, painting and music.
A yet further approach, such as that of Gunther Kress and Theo van Leeuwen is to focus on ‘modes’ and to study the multimodality of texts, that is, texts that use a variety of signs, such as image, language and sound (Ryan, 2014: 27).
In contrast to these approaches, Ryan (2014: 29) proposes a taxonomy that rests on three dimensions: semiotic, technical and cultural.
Thus, the semiotic dimension, as substance, includes such type of signs as image, sound, language and movement, which can be further analysed in terms of spatiotemporal extension, signifying dimensions, sensorial impact and mode of signification, for example, iconic, indexical or symbolic, to use the terms of C. S. Peirce.
Technical dimension includes not only media-defining technologies, such as film, television, photography and so on, but also any kind of mode of production and material support. Ryan notes that, In certain cases, the mode of production cannot be distinguished from the material support, such as in theatre or ballet, where the human body fulfils both of functions. In other cases, the mode of production is multilayered, such as in literature, which involves the technology of writing, with pen and paper, typewriter and paper or with the computer, and the technology of printing, the latter producing the material support of the book. In the case of multilayered modes of production, a distinction might be made between technologies that record and transmit other media, such as writing for language, books for writing and radio for speech and music, and technologies that capture life directly, such as photography, film and sound recording.
The cultural dimension addresses the public recognition of media as forms of communication and the institutions, behaviours, and practices that support them. In this category Ryan places those means of communication such as the press, the theatre or comics. She reasons that they are widely recognised as playing a significant cultural role but cannot be distinguished on purely semiotic or technological criteria.
On this basis, she defines three approaches to a media-conscious narratology:
a semiotic approach, which investigates the narrative power of language, image, sound, movement, face-to-face interaction, and the various combinations of these features;
a technical approach, which explores such issues as how technologies configure the relationship between sender and receiver, for example, one to one, few to many, many to many, and close or remote in either space or time, how they affect dissemination, storage, and cognition and what affordances certain types of material supports bring to storytelling; and
A cultural approach, which focuses on the behaviour of users and producers, as well as on the institutions that guarantee the existence of media. 
Space as a medium; Place as a medium; Time as a medium
In being defined as transmedial, the term ‘medium’ in the design of narrative environments is extended to include spatiality, placiality and temporality. That is, the notion of medium is taken deep into the territory that has been conventionally defined as ‘environment’. Thus, in the design of narrative environments, medium and environment are held in a chiasmic relation, such as discussed by Merleau-Ponty.
The question of the relationship between medium and environment opens up the further question of whether it is more proper to describe narrative environments as trans-semiotic or inter-semiotic rather that transmedial or intermedial, since any specific narrative environment may involve a cascade of media and environments, drawing upon signs and semiosis from across a range of different materialities, from the more tangible to the less tangible.
 Marie-Laure Ryan (2014: 44, n3) points out that Lars Ellestrom (2010) has developed a classification of media concepts that comes close to her own. Ellestrom proposes that there are ‘basic media’, which includes such semiotic categories as auditory text, still image and iconic body performance; ‘qualified media, such as film, dance and photography; and ‘technical media’, which realise or display basic and qualified media, for example a screen for television, a specific kind of paper for photography and the human body for dance.
Furthermore, Ellestrom contends that each medium has four modalities: material, such as the human body, paper and clay; sensorial, such as sight, hearing and taste; spatiotemporal, extending in time, space and/or both; and semiotic, such as convention, resemblance and contiguity.
Ryan suggests that each of these modalities could be subsumed under the semiotic category because they all concern the basic properties of signs, which could then be renamed ‘basic principle of signification’.
Ellerstrom, L. (2010) ‘The Modalities of media: a model for understanding intermedial relations’, in Ellestrom, L. (ed.) Media borders, multimodality and intermediality. Houndmills, Basingstoke, UK: Palgrave Macmillan.
Ryan, M.-L. (2014) ‘Story/worlds/media: tuning the instruments of a media-conscious narratology’, in Ryan, M.-L. and Thon, J.-N. (eds) Storyworlds across Media. Toward a Media-Conscious Narratology. Lincoln, NE: University of Nebraska Press, pp. 25–49.
Ryan, M.-L. and Thon, J.-N. (eds) (2014) Storyworlds across media: toward a media- conscious narratology. Lincoln, NE: University of Nebraska Press.