blindsight
There is a fascinating case study in Current Biology.
de Gelder et al. discuss a patient -- referred to as TN to protect his privacy -- who had two sequential strokes that damaged his brain. The parts of the brain that were damaged included the primary visual cortex in both hemispheres -- rendering the patient blind. However, the patient could still respond to some visual stimuli through a phenomenon called blindsight.
Even more interesting, the patient could still navigate around visual objects, while reporting being unable to see them and having no memory for what they were.
I have…