The use of virtual environments for survey spatial ability evaluation in topographical disorientation

Due to their interactivity and to the sense of presence they afford, virtual environments constitute an interesting opportunity for the study of spatial cognition (Péruch, Gaunet, 1998). Moreover, the organization of spatial knowledge into route and survey maps, derived from virtual environments exploration, appears to be nearly directly comparable to the learning obtained through the navigation of natural ones (Tlauka, Wilson 1996). According to this perspective we aimed in introducing a spatial test in virtual simulation in order to investigate the survey spatial ability in patients with topographical disorientation. Survey maps, in fact, are flexible representations of a higher level, capable to support abstract representations of the space, that provide agents with the possibility to infer and plan paths even in an unknown environment. The main aim of the study is in investigating where impairment in survey map organization could be the hub element for topographical disorientation manifestation in brain damaged subjects. In doing that, we introduce the “planning in advance task” in virtual environment, which constitutes an effective procedure to experimentally evaluate survey maps (Morganti, Carassa, Geminiani, 2006). With this procedure we tested the case of R.G., a 32 years old woman who suffered from a haemorrhagic small lesion into the right temporal lobe. Neuropsychological evaluation revealed a selective impairment in the acquisition of new spatial relationships, in absence of any other cognitive disorders. Virtual reality-based planning in advance task showed an inability to find one’s way in unknown environments, not referable to landmark recognition and memorization, the characteristic of which are correctly detected but not spatially located. Where compared with a control group formed by 40 female subjects matched for age and education the patient presented a survey-type performance significantly different from their average one. In particular, virtual reality-based evaluation highlighted in R.G. a selective impairment in inferring relationships among distant landmark, in planning shortcuts in order to find a target point and to revise path planning in order to avoid unexpected obstacles. Finally, deficiencies in planning tasks appear to be correlated with accuracy and hierarchical organization in sketch map task of an unfamiliar just explored large scale environment.