Using electroencephalogram to investigate stages of visual search in visually impaired computer users: Preattention and focal attention

Researchers have shown that computer users with impaired vision perform visual search more slowly than their fully sighted counterparts. However, little is known about intermediate stages of visual search that exist between stimuli detection and identification. Therefore, the primary focus of this research is to investigate 2 intermediate stages of visual search in visually impaired computer users: preattention and focal attention. A total of 10 volunteers, 1 participant who possessed normal vision and 9 participants possessing impaired vision, underwent clinical visual examinations consisting of assessments of visual acuity, contrast sensitivity, visual field, and color perception. The involvement of each participant's visual cortex while performing a continuous matching task of visual icons on a computer screen was recorded. Results demonstrated that additional time required by visually impaired computer users is not a result of delayed engagement of the visual cortex, but rather due to time spent in active search once the visual cortex has already been engaged. Directions for future research are provided.