Analysis of normal flicker sensitivity and its variability in the visuogram test.

Flicker sensitivity was measured in groups of younger and older adult observers to assess its mean values and the test-retest variability both between sessions and in a single session. Test-retest sensitivities differed by less than 15% but tended to decrease slightly in a session and increase slightly between sessions. Optical blur had little effect on the measured sensitivities, implying that they were not mediated by the edge information in the display. There were no significant differences between eyes other than those attributable to testing order. Within eyes, inherent variations in human flicker sensitivity accounted for about half of the variance, and within-session variability accounted for most of the remainder.