Spatial navigation in real and virtual urban environments: performance and multisensory processing of spatial information in sighted, visually impaired, late and congenitally blind individuals

Previous studies investigating how humans build reliable spatial knowledge representations allowing them to find their way from one point to another in complex environments have been focused on comparing the relative importance of the two-dimensional visual geometry of routes and intersections, multi-dimensional data from direct exposure with the real world, or verbal symbols and/or instructions. This thesis sheds further light on the multi-dimensional and multi-sensorial aspects by investigating how the cognitive processing of spatial information derived from different sources of sensory and higher order input influences the performance of human observers who have to find their way from memory through complex and non-familiar real-world environments. Three experiments in large-scale urban environments of the real world, and in computer generated representations of these latter (Google Street View), were run to investigate the influence of prior exposure to 2D visual or tactile maps of an itinerary, compared with a single direct experience or verbal instructions, on navigation performances in sighted and/or visually deficient individuals, and in individuals temporarily deprived of vision. Performances were analyzed in terms of time from departure to destination, number of stops, number of wrong turns, and success rates. Potential strategies employed by individuals during navigation and mental mapping abilities were screened on the basis of questionnaires and drawing tests. Subjective levels of psychological stress (experiment 2) were measured to bring to the fore possible differences between men and women in this respect. The results of these experiments show that 2D visual maps, briefly explored prior to navigation, generate better navigation performances compared with poorly scaled virtual representations of a complex real-world environment (experiment 1), the best performances being produced by a single prior exposure to the real-world itinerary. However, brief familiarization with a reliably scaled virtual representation of a non-familiar real-world environment (Google Street View) not only generates optimal navigation in computer generated testing (virtual reality), but also produces better navigation performances when tested in the real-world environment and compared with prior exposure to 2D visual maps (experiment 2). Congenitally blind observers (experiment 3) who have to find their way from memory through a complex non-familiar urban environment perform swiftly and with considerable accuracy after exposure to a 2D tactile map of their itinerary. They are also able to draw a visual image of their itinerary on the basis of the 2D tactile map exposure. Other visually deficient or sighted but blindfolded individuals seem to have greater difficulty in finding their way again than congenitally blind people, regardless of the type of prior exposure to their test itinerary. The findings of this work here are discussed in the light of current hypotheses regarding the presumed intrinsic nature of human spatial representations, replaced herein within a context of working memory models. It is suggested that multi-dimensional temporary storage systems, capable of processing a multitude of sensory input in parallel and with a much larger general capacity than previously considered in terms of working memory limits, need to be taken into account for future research.