The processing rate of visual information was measured by a backward masking technique in 12 university students (men; age range, 21-32 yr) with 20/20 vision who drank alcohol no more than once a week. A target stimulus (TS) of 4 randomly selected letters was presented to each subject for 15 ms, followed by a masking stimulus (MS) after an interstimulus interval (ISI). (The MS prevents further processing of the TS data from the visual sensory information storage into the short-term memory system. As the ISI increases, larger proportions of the information from the TS reach the short-term memory and can be reported by the subject.) Each subject was tested 30 min after finishing drinking 0, 0.414 and 0.828 g of alcohol/kg of body weight in a repeated-measures experimental design; 6 ISIS were employed ranging from -15 to 75 ms, plus a no-MS condition. Testing sessions, each consisting of 168 trials, were 1 wk apart. The number of correctly reported letters was significantly decreased after alcohol (P < .01) at the various ISIS. When no MS was presented performance was similar to that after placebo, indicating that with sufficient time for processing no information was lost from either sensory storage or short-term memory. After the low alcohol dose processing time was increased by about 5-7 ms and after the high dose about 15-20 ms. Alcohol impairs the rate at which information is processed.