Raster Scanning Can Improve Task Performance in Simulated Prosthetic Vision

Current challenges exist for cortical visual prostheses in presenting complex visual scenes. One of the major constraints is the number of electrodes that can be stimulated simultaneously, due to issues with electrical interaction between electrodes and the resulting complications in visual perception. To overcome this, studies have presented the outline of objects sequentially. However, this method has only been tested with simple visual stimuli, such as letters. We combined the strengths of both simultaneous and sequential presentation of phosphenes via a novel stimulation protocol named raster scanning. We tested this method using simulated prosthetic vision with a Virtual Reality headset and evaluated participants' visual abilities over three tasks. We recorded head movement data to investigate the various strategies participants employed to explore the visual scene. We found that raster scanning could improve task accuracy and reduce response time across three tasks. Moreover, raster scanning required less head movement to complete tasks. These results suggest that raster scanning binds visual cues more efficiently than head scanning alone. Our findings underscore the importance of sequentially presenting visual information and confirm the potential of cortical visual prostheses to provide functional vision, even under the current spatial and temporal constraints.