A Framework for Interpreting Distinct Patterns of Hemispatial Neglect

We report analyses of the performance of three stroke patients which reveal distinct patterns of spatially specific errors in reading and other perceptual tasks. These patterns of performance can be explained by proposing hemispatial neglect in different spatial coordinates in each case. Results from reading and perceptual tasks by two patients with right parietal damage, BPN and JOD (whose results have not been previously reported) are contrasted to those from a previously reported patient, NG. These contrasting patterns of errors provide support for a model of word and visual object recognition which assumes that these processes involve computing (at least) three distinct levels of representation with different coordinate frames. The data we report also provide evidence that hemispatial neglect can result from selective damage to any of these levels of representation - i.e. damage to a retinocentric, a stimulus-centered, or an object-centered level of representation. We show that this model provides a coherent framework for interpreting the various (and sometimes conflicting) patterns of hemispatial neglect and neglect dyslexia reported in the literature.