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Abstract

Survey estimates such as pointing, straight line distance estimation, or finding novel shortcuts to distant locations are common tasks. Although involved reference frames and brain areas were examined the underlying processing is widely unknown. We examined the development of survey knowledge with experience to tap into the underlying processes. Participants learned a simple multi-corridor layout by walking forwards and backwards through a virtual environment. Throughout learning, participants were repeatedly asked to perform in pairwise pointing from each segment border to each other segment border. Pointing latency increased with pointing distance and decreased with pointing experience, rather than learning experience. From this realization, we conclude that participants did not access an encoded representation when performing survey tasks, but instead performed an on-the-fly construction of the estimates which was quicker for nearby goals and quickened with repeated construction, but not with learning of the underlying elements. This could relate to successive firing of place cells representing locations along a route from the current location to the target, or the construction of a mental model of non-visible object locations. Furthermore, participants made systematic errors in pointing, for example, mixed up turns or forgot segments. Modelling of underlying representations based on different error sources suggests that participants did not create one unified representation when internally constructing the experimental environment. But instead, they constructed a unique representation at least for each orientation the environment was navigated. There was no indication that this separation changed with experience. We conclude that survey estimates are conducted on-the-fly and are based on multiple representational units.