Abstract
Several lines of evidence suggest that the ability to process visual temporal information may be significantly impaired after alcohol consumption. The clearest indication of impairment is the demonstration of a reduction in CFF (Carpenter, 1962; Pearson and Timney, 1998). By themselves, the available data show only that temporal processing is affected; they do not provide an explanation of the underlying mechanisms. One possibility is that alcohol causes a reduction in the speed of neural transmission in one or more visual subsystems. In order to explore this, we used a task that permits transmission efficiency to be estimated by allowing for a gross measure of interhemispheric transfer time (Poffenberger, 1912). Individuals were tested under both no-alcohol and alcohol conditions (approx. BAC 0.08 ml dl-1). In our first experiment, interhemispheric transfer time was assessed using a visual response latency measure to lateralized targets. Interhemispheric transfer time for a target presented along the horizontal meridian at various locations was significantly increased after alcohol consumption. We took a different approach in a second experiment. Subjects were required to make judgements of visual target onset precedence for targets presented in the bilateral and unilateral viewing conditions. Although results were in the appropriate direction after alcohol, the differences were small. These data demonstrate effects on transmission efficiency and provide preliminary evidence that the impairment in visual temporal processing after alcohol consumption is due to a reduction in the speed of neural transmission.
NSERC grant to Brian Timney