Estimating the Position of Simulated Phosphenes Using a Tactile Guide

A visual prosthesis provides usable visual information to the patient in the form of phosphenes, that is, punctate photic sensations seen after electrical stimulation. Stimulation via different electrodes results in phosphenes in different positions within the visual field. Simulation studies can provide data on the possible limitations of prosthetic stimulation. We used a head mounted screen to monocularly present constant or flickering light spots of different sizes, or luminance to normally sighted subjects. Subjects were asked to judge the location of the spots using a polar coordinate tactile guide; positioning average error and dispersion were analyzed. With the increase of eccentricity, the positioning average error and dispersion were also increased. The performances under large, stable and high luminance conditions were better than that under small, flickering and low luminance conditions, respectively. Repeated training sessions were shown to significantly improve the positioning performance. (C) Koninklijke Brill NV, Leiden, 2011BiophysicsPsychologyPsychology, ExperimentalSCI(E)EISSCI1ARTICLE2125-1402