Effects of alcohol on perceptual speed.

In moderate to heavy doses, alcohol adversely affects performance on many tasks, and perceptual speed is a component in most performance tasks. Nevertheless, studies of alcohol's effects on perceptual speed have been largely limited to critical flicker frequency and backward masking. The present study extends these limits. 16 men and 12 women were administered four temporal-factors tests before and after the ingestion of alcohol. The four tests were Simultaneity, Apparent Movement, Bistable Stroboscopic Motion, and Backward Masking. At the first postalcohol testing (mean BAC = 0.111), all four tests showed pre-posttest changes indicating slowed perceptual speed. Perceptual speed was still slowed when BAC decreased to .096. When mean BAC decreased to .076, however, only Simultaneity and Backward Masking were still significantly slowed. At moderate BACs and possibly at lower ones, the effects of alcohol on task performance appear to be mediated in part by slowed perceptual speed.