Subjects were required to perform four vigilance tasks each lasting 32 minutes. The tasks involved temporal discrimination with a simple motor response required for the shorter duration signal. The ratio of short to long duration signal was 1:2. The short duration signal persisted for 200 ms; the long duration signal, for 400 ms. Two modes of stimulus presentation were used--auditory and visual-- as well as two schedules of presentation--fixed interstimulus interval (2 s) and variable interstimulus interval (x-2 s). Electrooculographic and behavioral data were obtained. The results are summarized. Evaluation of the eyeblink alertness detector identified a number of problems with the device, which are summarized in the report.