Grasping the non-conscious: Preserved grip scaling to unseen objects for immediate but not delayed grasping following a unilateral lesion to primary visual cortex

Patients with damage to primary visual cortex can sometimes direct actions towards ‘unseen’ targets located in areas of the visual field that are deemed ‘blind’ on the basis of static perimetry tests. Here, we show that a patient with a complete right homonymous hemianopia after a V1 lesion remains sensitive to the width of objects presented in her blind field but only when reaching out to grasp them in ‘real-time’. A subsequent fMRI experiment revealed spared extra-geniculostriate pathways, which may mediate her preserved abilities. Taken together, the results support the view that visually guided movements can be mediated by pathways that do not support visual consciousness.

► A patient with a right homonymous hemianopia scales her grip to objects presented in her blind field. ► FMRI revealed evidence for spared pathways bypassing V1 that may mediate her preserved abilities. ► In summary, visually guided action can be mediated by pathways that do not support visual awareness.