Assessing Visual Mental Imagery in Cerebral Visual Impairment

Cerebral (cortical) visual impairment (CVI) is an umbrella term for visual disorders associated with maldevelopment of or damage to retrochiasmal visual processing areas of the brain, often (but not necessarily) in the absence of major ocular disease. Individuals with CVI may show lower-level visual function deficits, such as reduced acuity, contrast sensitivity, visual field impairment, and ocular-motor disorders. However, higher-order perceptual deficits, such as impaired visual search and image recognition, are also common. One aspect that has not been investigated is whether visual mental imagery is also impaired in these individuals. We used the Vividness of Visual Imagery Questionnaire (VVIQ; Marks 1973) to investigate differences in visual imagery abilities in individuals with CVI compared to age-matched controls. VVIQ and verbal IQ scores (WAIS-IV) were collected from 12 individuals with CVI (3 males, mean=22.58 years ± 5.32 SD) and 12 controls with neurotypical development (4 males, mean=22.42 years ± 3.35 SD). There was no significant difference in age [t(18.952)=0.091, p=0.929, d=0.037] or verbal IQ [meanCVI=108.50 ± 29.266 SD, meanControls=119.73 ± 13.425 SD, t(12.365)=-1.111, p=0.288, d=-0.502] between the two groups. However, we found that individuals with CVI had significantly lower VVIQ scores (mean=34.42 ± 18.57 SD) compared to controls (mean=63.83 ± 14.30 SD) [t(20.650)=-4.347, p=0.0003, d=-1.775]. We also found that verbal IQ was not significantly predictive of VVIQ in either group (CVI: [F(1, 8)=0.090, p=0.772, R2=0.013], Control: [F(1, 10)=0.101, p=0.294, R2=0.011]), indicating that reported visual imagery in CVI did not vary as a function of verbal ability. These results suggest that impaired visual mental imagery may also be a feature related to the complex clinical profile of CVI.