Modeling visuospatial perception in neglect patients

The spatial distortion hypothesis is one of several theories that explain certain aspects of neglect in patients with right parietal lesions. To determine whether a distorted representation of space can account for the performance of neglect patients in different visuospatial tasks, we asked 26 neglect patients to: (1) bisect horizontal lines and (2) to compare the width of two horizontally aligned bars. A simple mathematical model compatible with the idea of a stationary distortion of represented space in egocentric coordinates explained the results of the line-bisection task. A second model that had basically the same structure and was compatible with the idea of a distorted egocentric representation based on a dynamic remapping of space approximated the size-comparison data. These results support the view that abnormalities observed in the line-bisection and size-comparison tasks are due to a distorted internal representation of the external world. Certain findings suggest that this distortion could be based on a dynamic mapping of space determined by the distribution of visuospatial attention.