Effects of alcohol on perceptual speed

In moderate to heavy doses, alcohol adversely affects performance on many t asks, and perceptual speed is a component in most performance tasks. Nevert heless, studies of alcohol's effects on perceptual speed have been largely limited to critical flicker frequency and backward masking. The present stu dy extends these limits. 16 men and 12 women were administered four tempora l-factors tests before and after the ingestion of alcohol. The four tests w ere Simultaneity, Apparent Movement, Bistable Stroboscopic Motion, and Back ward Masking. At the first postalcohol testing (mean BAC = 0.111), all four tests showed pre-posttest changes indicating slowed perceptual speed. Perc eptual speed was still slowed when BAC decreased to .096. When mean BAC dec reased to .076, however, only Simultaneity and Backward Masking were still significantly slowed. At moderate BACs and possibly at lower ones, the effe cts of alcohol on task performance appear to be mediated in part by slowed perceptual speed.