Unilateral spatial neglect in dissociable frames of reference: a comment on Farah, Brunn, Wong, Wallace, and...

We comment on a paper by Farah et al. in which it is claimed that averaged performance on a letter naming task by a group of patients with left unilateral spatial neglect (USN) provides evidence that spatial allocation of attention is defined by environment-centered and viewer-centred coordinates, but not by object-centred coordinates. We re-analyze the raw data from that paper, and present statistical analyses of the data from individual subjects which show dissociations in the coordinate frames used by the individual subjects with USN. The data from individual cases demonstrate that object-centered USN occurs alone (without evidence of USN in other reference frames) in some cases, and in association with USN in other reference frames other cases. In contrast to the conclusions drawn from the group performance, results from individual subjects provide evidence for the role of dissociable frames of reference, including an object-centred coordinate frame, in the spatial allocation of attention.