Abstract
Our purpose was to show how the modification of visual information available to moving observers can change the way they perceive their path and the structure of the environments they pass through. Stimulus trials simulated locomotion across a tree-filled plane while the gaze was directed at a particular tree. In the first experiment we varied the angle between the line of gaze and the simulated direction of movement (GMA) between 0° and 20°. In the second experiment we used either inward displacement (ID) of some objects (moving towards the fovea) or other flow patterns. After each trial, participants drew their path or the position of the particular tree on a schematic map of the environment. In the first experiment, with respect to the fixation point, as GMA increased so did the shift in the drawn paths, and we measured a significant correlation between the two. In the second, ID changed the accuracy of depth representation for the most distant objects in the visual field.
In conclusion, the strong relation between GMA and the reproduced paths, even though they are discrepant from the true paths, suggests that the maintenance of course in the real world may not be based on a maplike mental representation of one's trajectory. In addition, opposite motions in the same region of the visual field (as encountered with ID patterns), may significantly modify the information used for integrating spatial relationships in the environment. The attractive power of these regions in gaze control may also renew our theoretical interest in selective attention.
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