EFFECTS OF MODERATE BLOOD-ALCOHOL CONCENTRATIONS ON SPATIAL AND TEMPORAL CONTRAST SENSITIVITY

Objective: In order to gain a more complete picture of the influence o f alcohol on visual performance, we measured contrast sensitivity for a range of spatial and temporal frequencies in individuals with modera te blood alcohol concentrations (BACs). Method: Subjects were tested a t blood alcohol concentrations of 0.06% in both the rising and falling phases of absorption. In the first part of the study, the performance of two men and four women on a number of simple screening measures an d static contrast sensitivity was measured. In the second part (four m en and three women), the grating patterns were contrast reversed at fo ur different rates, allowing us to assess the effects of alcohol on te mporal processing. The second study examined the relationship between blood alcohol concentrations and contrast sensitivity. Results: Althou gh few significant changes in performance were found on the simple scr eening tests, we observed a significant reduction (43%) in stationary contrast sensitivity at the 0.06% BAG. This change in performance was greater at low and high spatial frequencies than at moderate ones. At high temporal frequencies, the reduction in sensitivity was 2.5 times that seen for lower temporal frequencies. With higher blood alcohol co ncentrations, the decrease in performance was found to be greatest for the high and low spatial frequencies. Conclusions: These data suggest that alcohol produces visual deficits that are not attributable to pu rsuit eye movements. It is suggested that these visual deficits, combi ned with changes in ocular-motor control and attentional deficits, may have a strong effect on performance under the influence of alcohol.