Impaired visuospatial processing in cerebral visual impairment revealed by performance on a conjunction visual search task
Claire E. Manley, Corinna M. Bauer, Peter J. Bex, Lotfi B. Merabet
Abstract
Cerebral visual impairment (CVI) is a brain-based visual disorder associated with injury and/or maldevelopment of central visual pathways. Visuospatial processing impairments are a cardinal feature of the complex clinical profile of individuals with CVI. Here, we assessed visuospatial processing abilities using a classic conjunction search task. Twenty-three (23) individuals previously diagnosed with CVI (mean age 18.55 years ± 4.98 SD) and 37 controls with neurotypical development (mean age 21.11 years ± 4.56 SD) participated in the study. Subjects were instructed to search for a two-feature target (a white or black letter "O" or "C") presented among a varying number of surrounding distractors (set sizes ranging from 1 to 32 items). Behavioral outcomes collected were reaction time (RT), accuracy, as well as slope and intercept values derived from the RT x set size function. Overall, participants with CVI took longer and were less accurate in finding the target than controls. Analysis of RT x set size functions revealed a profile consistent with less efficient search and slower visual orienting responses as indexed by higher slope and intercept values, respectively. These results are consistent with clinical reports of impaired visuospatial processing abilities and deployment of visual selective attention in individuals with CVI.