Alcohol and vigilance performance: effect of small doses of alcohol on simple visual reaction time.

The effects of small doses of alcohol were tested in a vigilance setting. Subjects were repeatedly tested during three 30-min. sessions. The stimulus event was a visual light located in front of subjects. The average intersignal interval was 3.75 sec., and the dependent measure was simple reaction time. Analysis indicates that alcohol produced a skewness in the RT-distribution with time on task; the longer reactions increased more than the shorter ones. Especially the extremely long reactions (blockings) increased markedly with time on task under alcohol. Results were discussed in relation to other studies reporting divergent results in similar test situations.