Alcohol effects on signal detection performance.

The acute effects of alcohol (0.7 g/kg) on visual signal detection performance and critical flicker fusion frequency (CFF) of normal volunteers were investigated using a signal detection theory analysis. When signal probability was low, alcohol affected the stimulus sensitivity and the reaction times of hits. Under a high signal probability these indices were not affected, whereas the response bias did not change after the administration of alcohol under both signal probabilities. CFF values were not altered by alcohol. A correlation was found between the magnitude of the alcohol effect and the performance level under placebo. Changing the signal probability caused significant differences between the sensitivity measures, the response bias measures and the reaction times of hits. It is concluded that alcohol affects signal detection performance under conditions of low signal probability. Individuals with a relatively low performance level are more susceptible to the effects of alcohol.