In performing search tasks, the visual system encodes information across the visual field at a resolution inversely related to eccentricity and deploys saccades to place visually interesting targets upon the fovea, where resolution is highest. The serial process of fixation
, punctuated by saccadic eye movements, continues until the desired target has been located. Loss of central vision restricts the ability to resolve the high spatial information of a target, interfering with this visual search
process. We investigate oculomotor adaptations to central visual field loss with gaze-contingent artificial scotomas.
Spatial distortions were placed at random locations in 25° square natural scenes. Gaze-contingent artificial central scotomas were updated at the screen rate (75 Hz) based on a 250 Hz eye tracker. Eight subjects searched the natural scene for the spatial distortion and indicated its location using a mouse-controlled cursor.
As the central scotoma
size increased, the mean search time increased [F(3,28) = 5.27, p = 0.05], and the spatial distribution of gaze points during fixation
increased significantly along the x [F(3,28) = 6.33, p = 0.002] and y [F(3,28) = 3.32, p = 0.034] axes. Oculomotor patterns of fixation
size, and saccade
duration did not change significantly, regardless of scotoma
There is limited automatic adaptation of the oculomotor system after simulated central vision loss.