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 vis ual search more slowly than their fully sighted counterparts. However, litt le is known about intermediate stages of visual search that exist between s timuli detection and identification. Therefore, the primary focus of this r esearch is to investigate 2 intermediate stages of visual search in visuall y impaired computer users: preattention and focal attention. A total of 10 volunteers, 1 participant who possessed normal vision and 9 participants po ssessing impaired vision, underwent clinical visual examinations consisting of assessments of visual acuity, contrast sensitivity, visual field, and c olor 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 visuall y impaired computer users is not a result of delayed engagement of the visu al cortex, but rather due to time spent in active search once the visual co rtex has already been engaged. Directions for future research are provided.