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Sighted Subjects (sighted + subject)

Distribution by Scientific Domains

Medical Sciences	50%

Selected Abstracts

Assessment of sensory substitution prosthesis potentialities in minimalist conditions of learning

APPLIED COGNITIVE PSYCHOLOGY, Issue 4 2006
Colline Poirier
Pattern recognition with a prosthesis substituting vision by audition was investigated. During 15 1-hour sessions, nine blindfolded sighted subjects were trained to recognise 2D patterns by trial and error. In addition to a global assessment, recognition of pattern element nature (vertical bars, horizontal bars,), element size and element spatial arrangement were independently assessed for each pattern. Influence of experimental parameters (complexity level of patterns, exploration number of a pattern) on recognition was studied. Performances improved over sessions. As a rule, patterns element nature was less well recognised than element size and spatial arrangement. Experimental parameters influenced pattern recognition performance. Results are discussed in relation with auditory and visual perception as well as in the perspective to implement a learning protocol for future users of prosthesis. Copyright © 2006 John Wiley & Sons, Ltd. [source]

Auditory substitution of vision: pattern recognition by the blind

APPLIED COGNITIVE PSYCHOLOGY, Issue 5 2001
P. Arno
Pattern recognition in a computer environment was investigated in 6 early blind and 6 blindfolded sighted subjects using auditory substitution of vision. Subjects had to scan visual patterns displayed on a PC screen by moving the pen of a graphics tablet, which lead to corresponding displacements of the cursor on the screen. A small screen area centered on the pointer was then translated into sounds according to a visual-auditory transcription code. Subjects were trained to learn this code during 12 one-hour sessions. Performance of both groups significantly increased with practice. This indicates that mental representations of visual patterns can be acquired through the auditory channel, even in the absence of visual experience. Moreover, blind subjects performed significantly better than sighted subjects did. This could be interpreted as a result of partial compensation for their loss of vision. Pattern recognition in a computer environment is thus possible using a fairly natural vision-to-audition coding scheme. Copyright © 2001 John Wiley & Sons, Ltd. [source]

Estimation of Phosphene Spatial Variability for Visual Prosthesis Applications

ARTIFICIAL ORGANS, Issue 5 2010
Iyad Obeid
Abstract Visual prostheses are the focus of intensive research efforts to restore some measure of useful vision to blind or near-blind patients. The development of such technology is being guided to an extent by tools that simulate prosthesis behavior for healthy sighted subjects in order to assess system requirements and configurations. These simulators, however, typically assume purely deterministic phosphene properties and thus do not apply any variability to phosphene size, intensity, or location. We address this issue by presenting data on phosphene variability measured in a blind human subject fitted with an optic nerve prosthesis. In order to correct for normal limitations in human-pointing accuracy, the experimental conditions were repeated with sighted subjects. We conclude that identical optic nerve stimulations can result in phosphenes whose perceived locations vary by up to 5° of deviation angle and 10° of position angle. The consistency of phosphenes presented in the peripheral field of view can vary by an additional 3°. [source]

What do patients with glaucoma do when they search and look at everyday scenes?

ACTA OPHTHALMOLOGICA, Issue 2009
ND SMITH
Purpose To test the hypothesis that patients with bilateral glaucoma exhibit different eye movements compared to normally-sighted subjects when viewing computer displayed photographs, or searching for features or items within them. Methods Thirteen glaucoma patients and 17 age-matched subjects with normal vision viewed 28 randomised digital photographs of various everyday scenes displayed on a computer screen for 3 seconds each. Subjects were instructed to view the images as they would when looking at a slideshow. The subjects then viewed another set of images, but were timed to find a feature or item in the scene. Eye movements were simultaneously recorded using an Eyetracking system. Results In the passive viewing experiment, there was a significant reduction in the average number of saccades for glaucoma patients compared to controls (p<0.0001). In addition, average fixation duration was longer and the average area scanned was more restricted in patients compared to controls. In the search task glaucoma patients took, on average, longer to find the objects (p<0.0001) compared to controls. For this task, saccades were still reduced in number. In some cases, individual scanning patterns appeared related to the type and nature of the binocular visual field defect. Conclusion Eye movement behaviour in patients with glaucomatous defects in both eyes differ from normal-sighted subjects when viewing images and photographs. These patients with glaucoma find it more difficult to locate items within scenes compared to normally sighted subjects. Acknowledgements: This work is generously supported by an unrestricted grant from the Special Trustees of Moorfields Eye Hospital. [source]