1. Disorders of Attention Orienting
Neglect, Extinction and Balint’s Syndrome

2. Hemispatial Neglect
Unilateral lesion to Parietal or Temporo-Parietal are
Patients present with vision problems, but are not “blind”
Rather, they fail to apprehend (and interact appropriately with) stimuli in the contralesional field

3. Hemispatial Neglect
E.g. line bisection task

4. Hemispatial Neglect
E.g. reproducing visual forms

5. Extinction Extinction is a more complicated aspect of neglect
Patients fail to apprehend objects in the contralesional field when stimuli are present in the ipsilesional field

6. Balint’s Syndrome Bilateral parietal lesions
Patients fail to apprehend all but one of simultaneously presented objects at the same location
Condition is object-based, not location-based
Multi-colored dots are properly seen if they are connected by lines

7. Investigation of Neglect with Cue-Target Paradigm
Posner et al. (late 1970s) used a cue-target paradigm
Parietal Lobe patients are profoundly impaired only when invalidly cued to attended to the ipsilesional (good) side

8. Investigation of Neglect with Cue-Target Paradigm
Interpretation: parietal lobe mediates a disengagement of attention in order to shift to another stimulus
Right parietal lesions tend to be more disruptive
Indicates that Rt. Parietal is disproportionately involved in spatial orienting in most people

9. Attention “Disorders” in Normal Subjects
A number of illusions/demonstrations exist that give us a hint of what it might be like to have a disorder of attention
Inattentional or “change” blindness can occur when something interferes with the normal attention orienting system
Object substitution demonstrates consequence of attending to only one of two objects at the same location