Visual Prosthesis
B. The visual percept elicited by electrical stimulation of area V1

A similar procedure was employed to determine what the size is of the image created by the electrical stimulation. This is shown in Figure 1C and 1D. In 1C data are shown when two targets were used and the size of one was varied. When the two targets were identical in size the monkey chose the targets with equal probability. Figure 1D shows performance when the upper target, whose size was systematically varied, as shown on the X axis, was paired with electrical stimulation. Data are shown from two sessions. The equivalence point is at 16 minutes of visual angle diameter size for the visual stimulus indicating that this is the size of the percept produced by the electrical stimulation. Varying the amount of current delivered did not significantly shift the equivalence point for size.