COORDINATE FRAMES FOR NAMING MISORIENTED CHIMERICS - A CASE-STUDY OF VISUOSPATIAL NEGLECT

A persistent line bf inquiry for the students of visuo-spatial neglect has involved the perceptual frame of reference respect to which the n eglected region of space is defined. On standard testing conditions vi ewer-centered and object-centered systems of coordinates are confounde d. In order to disambiguate these two reference frames FB, a patient w ith severe left visual neglect consequent upon a right parieto-tempora l haemorrhage, was asked to identify chimeric figures presented at dif ferent orientations. FB continued to recognize poorly the left side of chimeric figures even when the display was rotated 90 degrees clockwi se or anticlockwise so that the 'left' of the chimeric fell on the pat ient's egocentric up or down, respectively. The result suggests that, at least under the present testing conditions, unilateral neglect is t ied to the principal (top-bottom) axis of the object. Object-centered vs. (viewer-centered) representational accounts of this finding are di scussed.