Representation of impossible worlds in the cognitive map.

It is often assumed that humans represent large-scale spatial environments as cognitive maps, but the exact features of these representations are still unclear. We investigate the structure of this representation with the impossible worlds paradigm by testing whether the information provided by virtual environments (VEs) with arbitrary violations of geometrical rules is rectified ("distorted") to become compatible with a map-like structure. The experiments were conducted in virtual reality using a natural locomotion interface. The subjects' task was to explore possible and impossible VEs carefully to achieve a "full understanding". After each trial, they had to "blindly" reproduce the path through the environment from memory in a VE with impoverished visual cues. We have found no evidence for angular or configurational distortions or alterations in the blind reproductions of impossible VEs. Blind reproduction indicates that impossible VEs do not require a transformation into a "possible" format to make them fit into the cognitive map. This suggests that the representation may not be similar to a map in a bounded sense of interpretation but requires more generalized concepts for its understanding.