Abstract
The general notion of visual development is that basic visual functions develop before more complex ones. Here, we report a developmental case that seems to contradict this notion: LS, a 26 y.o. woman, shows severe impairments in mid-level, but intact higher-level vision. LS was first investigated in 2006 (age 16) due to difficulties in mathematics: Anamnesis revealed no previous illnesses/incidents that might have caused problems in visual abilities, but testing showed severe impairments in line and form discrimination. Since April 2016 we have the opportunity to re-assess LS: She has obtained her driver's license at age 18 and is driving since then, has finished high-school and is in vocational training. Visual acuity is in the normal range when measured with numbers or letters, but impossible to test with Landolt-C or Lea-Symbols. Color vision is normal. LS is able to process form-from-motion when it is biological, e.g. point-light-stick-figures, but not with simple forms. LS failed the screening test of the VOSP and showed deficits in five of the eight subtests, while she performed normally on incomplete letters, dot counting and position discrimination. She is fast and accurate in naming letters as well as line-drawings of common objects in the BORB, but markedly slowed with two overlapping items, and unable to perform the task with three. LS shows peculiar eye movements, consummately tracing lines and outer contours with her gaze, or using her fingers with 3D-objects. LS shows normal to above average performance on the Benton and the CFMT. She performed both tests swiftly and without hesitation. LS is aware of her visual "peculiarities" and her "tracking strategy". LS's visual profile seems to suggest dissociations in the development of mid-level and higher-level visual functions, which we will be testing further—both behaviorally as well as through neuroimaging—in the upcoming months.
Meeting abstract presented at VSS 2017