Electrophysiological and psychophysical tests of age-related changes in vision

Abstract

There is evidence from the psychophysical literature which suggests that low spatial frequency-high temporal frequency visual input is distinctly impaired in older observers. We are investigating these changes by measuring evoked potential amplitudes elicited by gratings of 0.6 and 6 cycles/deg flickered at 15 and 7.5 Hz, respectively, presented at a variety of contrasts. Three groups of subjects (young, middle-aged, and older) were composed of ten males each. The slope of the function relating VEP amplitude to stimulus contrast provides an index of visual system gain at low grating contrasts and serves as the dependent measure of the study. The psychophysical method of magnitude estimation is being employed as well to determine if age related changes in electrophysiological measures of amplitude are in agreement with changes in perceived contrast.