Assessment of Human Visual Performance with a Swept Evoked Potential Technique
Abstract
Methods have been perfected for telling how well a person can see by direct measurement of his brain's response. Visual performance is measured in terms of contrast sensitivity and the acuity limit. The acuity limit is similar to the resolution limit measured by familiar Snellen eye charts. Contrast is familiar from the contrast control of TV sets; fading out contrast until very faint light-dark differences are reached provides a means of testing sensitivity to large patterns (a ship at sea in fog), where resolution of fine detail is not the problem. An observer with scalp electrodes over the visual areas of his brain views striped patterns on a TV monitor. Modern signal retrieval techniques are used to enhance weak visual responses in the noisy signals coming from the scalp electrodes. The specific aims of the contrast have all been realized, providing (1) validation of the techniques, (2) generation of evidence that contributions from the newly discovered X and Y visual pathways can be separated in the gross scalp potential with this new technique, and (3) identification of noise contamination is some observed responses. These research areas are considered in turn.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1984
- Accession Number
- ADA144682
Entities
People
- J. I. Nelson
Organizations
- NYU Langone Health