3 Method

In order to answer these questions, we chose to develop a partially simulated multimodal system (Wizard of Oz technique). Our objective was to force the interaction as little as possible while limiting the development cost of the system and to free us from the current technological limitations at exploratory ends centered on new modalities.

3.1 Subjects

Ten subjects took part in this experimental phase; they all had an electronic mail and were regular users of Internet but none was a computer specialist.

3.2 Task and nature of the modalities tested

In order to put the subjects in a situation of realisation of a familiar task, they were asked to use an application of consultation of electronic mail by means of a pocket computer (PDA Jornada 540 series, Hewlett Packard) which was connected, for the purposes of the experimentation to their personal electronic mail.

Four modalities studied were implemented:

the vocal modality is presented as a mode of interaction in natural language without particular constraints (no preset statements to be used by the subjects);
tactile modality, which requires a stylet to point the command buttons ;
gestural modality, which relies on a preset code which forces one to hold the PDA in one hand and to carry out the gesture with the free hand in front of the apparatus;
improperly qualified modality and temporarily "embodied", which consists of associating commands with certain preset handling of the artefact (changes of orientation, various movements, etc.).

Only tactile modality was really implemented, the other modalities were simulated by the accomplice thanks to an identical interface and a numerical video system.

Figure 4.1: Implementation of the tactile, gestural and "embodied" modalities

Each modality allowed a realisation of the same set of commands with the tactile modality as a reference.

3.3 Experimental procedure and platform

The activity of the subjects during the sessions (15 minutes average duration) was recorded by means of various sensors ( cameras , sensors of system events). The experimental sessions were preceded by a training and recall phase, and were spaced over several days. They were immediately followed by autoconfrontation which was video-recorded.