Figure 1. Data collected from ten subjects, together with median sensitivity marked as a darker line.

(a) Temporal contrast sensitivity for human observers has previously been reported to drop to zero (the critical flicker fusion rate) near 65 Hz. We duplicate those findings when the modulated light is spatially uniform. (b) When the modulated light contains a high frequency edge in the spatial domain, we measure sensitivity above 500 Hz, much higher than the previously reported rate.