Patrick Pe ´ ruch peruch@lnf.cnrs-mrs.fr Daniel Mestre Centre de Recherche en Neurosciences Cognitives CNRS, 31 Chemin Joseph Aiguier 13402 Marseille Cedex 20, France Between Desktop and Head Immersion: Functional Visual Field During Vehicle Control and Navigation in Virtual Environments Abstract The effects of available visual information in the periphery (enlargement of the func- tional visual field) on performance in navigation were evaluated in an experimental setup searching for a ‘‘compromise’’ between desktop and head-immersion situations. A Fixed Vision condition (fixed display) and two Mobile Vision conditions (head-track- ing with a visual field of variable width) were compared in six virtual environments of different complexity and in four successive sessions. First, a global improvement in performance throughout the sessions revealed a gradual integration of the properties of the simulation device. Second, performance was higher in the Mobile Vision condi- tions, as shown by the smoothness of the subjects’ paths (sharp curves could be nego- tiated without stopping), indicating the importance of a wide functional visual field. In conclusion, the need to design realistic and functionaly efficient human-machine inter- faces for navigation is discussed. 1 Introduction The definition of the content and format of visuospatial information avail- able to the operator is one of the major human factors in remote-controlled situations. In such situations, although the vehicle under control is out of the operator’s direct sight, visual control remains the dominant mode in most cases. Indeed, ‘‘direct’’ visual perception is replaced by images produced by video cameras on-board the vehicle (Pe ´ruch, Mestre, Pailhous, & Savoyant, 1993). The choices made concerning the information given to the operator necessarily modify the specific conditions under which control of the vehicle’s displacement is achieved. These modifications, as well as the difficulties they create for the operator, raise many questions, including the nature and percep- tual bases of navigation. With respect to the perception of the displacement of the vehicle, the static operator lacks kinesthetic and vestibular information which is usually associated with self-motion. In such purely visual conditions, the vehicle’s orientation and movement control are difficult for many reasons. First, part of the difficulties arise from the fact that depth and distance percep- tion are distorted by the video interface. Second, problems may result from missing or partial ground perception, or from the fact that part of the vehicle cannot be perceived on the video terminal (Mestre, Cavallo, & Pe ´ruch, 1986; Presence, Vol. 8, No. 1, February 1999, 54–64 r 1999 by the Massachusetts Institute of Technology 54 PRESENCE: VOLUME 8, NUMBER 1