Visual imperception in brain-injured adults: multifaceted measures.

Visual imperception denotes the disorders of perceptual functioning commonly associated with unilateral brain injury. Typically the same half of the visual fields of both eyes are affected on the side opposite to that of the brain injury. The disorder may have a sensory or an attentional basis or both, moreover, the patient is often not aware of the problem. The condition interferes with daily activities including reading and navigating abilities, and it increases the likelihood that a person will have accidents. Thus, it becomes an obstacle to rehabilitation. Two comprehensive tests for visual imperception, Search-A-Word (SAW) and Speeded Reading of Word Lists (SRWL), were administered to a large sample of brain-injured and nonbrain-injured adult rehabilitation patients. Measures included: search times for left- and right-side targets, words missed at either margin, completion rates, errors on displaced words, and within-span errors. Right hemisphere brain injury was reliably associated with errors on the left side; left hemisphere brain injury was associated with overall poor performance. A factor analysis of performance measures revealed three major independent factors: (1) left spatial hemi-imperception, (2) lateral scanning dysfunction, and (3) left foveal hemi-imperception. These findings support a neurosensory-based view of imperception, especially in brain-injured persons. Finally, differential assessment of these problems is essential for comprehensive rehabilitation.