Interferences and conflicts of schemes in using professional tools: The case of a navigation cartographic file

The paper claims that interferences of schemes might explain difficulties o bserved by operators in using professional tools. The argumentation is deve loped on the case of a cartographic file, designed to be used by rescue ser vices when going to an intervention place. The proposed hypothesis is that procedures required for efficient use of such a tool may interact with pree xisting schemes, which act as precursors both in a constructive way (as bei ng based on similar invariants) and in a restrictive way (as triggering a d ifferent organisation of action). Moreover, several schemes may be involved , whose interaction may lead to conflicts. The notion of dominant scheme is presented as an invariant organisation of action which is valid for a wide class of situations, difficult to inhibit, and shared by a large community of actors. The cartographic file is analysed from the point of view of the required procedures of use and of the possible precursors schemes, which m ight conflict. Three schemes are identified : the scheme of reading, a sche me used in plane representation, and a scheme for indexing and ordering ite ms in a sequential file organised as a book. An experimental analysis is pr esented : beginners and experienced firefighters were asked to perform thre e type of tasks, for analysing : 1 / how they organise a small-scale cartog raphic file, and index its items; 2 / what their knowledge of the structure of the professional cartographic file is; and 3 / how they perform a navig ation task with two organisations of a cartographic file : the professional one, and a modified file organised in coherence with a scheme of indexatio n. Results confirm the existence of interferences between schemes, and show the existence of a dominant scheme for indexation, based on the alphanumer ical order. In the population of professionals, the two schemes of reading and of plane representing act as precursors for structuring a cartographic file. The dominant scheme for indexing and ordering items sequentially orga nised in a book is in conflict with the coding of items in the professional tool. As a consequence of this study, modifications were introduced in ord er to enhance navigation through the file, without engaging in a strong mod ification of the spatial coding, and training was designed in order to prom ote a more operative representation of the cartographic file by its users.