ALCOHOL AND WORKLOAD AS FACTORS AFFECTING THE DETECTION OF ANGULAR-ACCELERATION

Introduction: Previous findings have demonstrated that a low blood alc ohol concentration (BAG) decreases subjects' ability to detect changes in angular motion and that this effect persists after the BAC returns to zero. Methods: Angular motion thresholds of six alcohol and six pl acebo subjects holding pilots' certificates were obtained under both l ow and high task load conditions. The alcohol subjects were tested und er double blind conditions in an enclosed simulator apparatus prior to drinking, after drinking (mean BAC = 0.038%), and at a time when the alcohol subjects' BACs had reached zero. Results: Alcohol subjects' me an threshold values for the three threshold test sessions were 0.361, 0.512, and 0.465 degrees . s(-2) and 0.292, 0.422, and 0.379 degrees . s(-2) for the high and law cask conditions, respectively. Correspondi ng values for placebo subjects were 0.364, 0.37, and 0.356 degrees . s (-2) for the high task load condition and 0.311, 0.317, and 0.312 degr ees . s(-2) for the low task load condition. Statistical analyses show ed significant task load and sessions effects (p < 0.025). Significant alcohol by test sessions interactions were found for both high and lo w task load conditions (p < 0.01) with subsequent t-tests showing no a lcohol-placebo differences for the pre-alcohol test session, but signi ficant alcohol-placebo differences for the alcohol test session and th e test session conducted after the subjects' BACs returned to zero. Co nclusions: The results indicate that the increased threshold for detec ting changes in angular motion found after alcohol ingestion is relati vely insensitive to task workload and, thus, it is unlikely that atten tional changes underlie the threshold increase. These data together wi th the finding that an elevated threshold can persist after BAC reache s zero suggest that the threshold increase after alcohol ingestion ref lects changes in vestibular functioning.