Visibility of temporal light artefact from flicker at 11 kHz

A flickering light can be seen during a saccadic eye movement as a pattern of contours known as a phantom array. On repeated pairs of trials, observers made saccades across a narrow (1 arc minutes), bright (10−4 cd/m2) source of flickering light and were required to detect the phantom array. On one of each pair of trials, chosen at random, the light flickered at 60 kHz and on the other at a frequency chosen in the range 1–11 kHz. In two such studies, a few observers were reliably able to discriminate 11 kHz from 60 kHz on the basis of the visibility of the phantom array. The average threshold at which the array was visible was about 6 kHz and therefore double that previously obtained with larger targets. Those observers who were able to see the phantom array tended reliably to report more symptoms of visual discomfort in everyday life.