Dissociation between goal-directed and discrete response localization in a patient with bilateral cortical blindness
Buetti, S., Tamietto, M., Hervais-Adelman, A., Kerzel, D., de Gelder, B., & Pegna, A. J.
Dissociation between goal-directed and discrete response localization in a patient with bilateral cortical blindness. Journal of Cognitive Neuroscience, 25
(10), 1769-1775. doi:10.1162/jocn_a_00404.
We investigated localization performance of simple targets in patient TN, who suffered bilateral damage of his primary visual cortex and shows complete cortical blindness. Using a two-alternative forced-choice paradigm, TN was asked to guess the position of left-right targets with goal-directed and discrete manual responses. The results indicate a clear dissociation between goal-directed and discrete responses. TN pointed toward the correct target location in approximately 75% of the trials but was at chance level with discrete responses. This indicates that the residual ability to localize an unseen stimulus depends critically on the possibility to translate a visual signal into a goal-directed motor output at least in certain forms of blindsight.