Psychophysics of prosthetic vision: II. Stochastic sampling, the phosphene image, and noise

Luke E. Hallum, Spencer C. Chen, Shaun L. Cloherty, Nigel H. Lovell

Research output: Chapter in Book/Report/Conference proceedingConference PaperResearchpeer-review

7 Citations (Scopus)


Stimulation of the diseased retina via an intraocular electrode array is a proposed means of restoring some vision to the profoundly blind. A prosthetic device to this end would involve post-implantation calibration (analogous to cochlear implant fitting), wherein the subject indicates those discrete positions in the visual field where luminous percepts are elicited. This procedure would be a source of noise, because the indicated positions would only approximate the actual positions in the visual field. Put differently, the procedure introduces sampling jitter, and would therefore affect clinical outcomes such as mobility and reading speeds. The nature of this noise is the concern of the present paper; we derive an expression for the noise power spectrum as it relates to the statistical nature of the sampling jitter. We show that, generally, jitter has greater effect on higher spatial-frequencies, that is, those areas of the implantee's visual perception that represent fine detail are more prone to noise. More specifically, the noise spectrum depends on the characteristic function of the random variable describing the sampling jitter. Our results signal the need for experimental work that characterizes sampling jitter in implantees, plus the need for simulations that allow a better understanding of perception and the noisy phosphene image.
Original languageEnglish
Title of host publication2006 28th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, Vols 1-15
Number of pages4
Publication statusPublished - 2006
Externally publishedYes
EventInternational Conference of the IEEE Engineering in Medicine and Biology Society 2006 - Marriott Hotel, New York, United States of America
Duration: 31 Aug 20063 Sep 2006
Conference number: 28th (Proceedings)


ConferenceInternational Conference of the IEEE Engineering in Medicine and Biology Society 2006
Abbreviated titleEMBC 2006
Country/TerritoryUnited States of America
CityNew York
Internet address

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