Effects of ethanol on working memory and attention in pigeons.

To determine whether the effects of ethanol on working memory are mediated by a secondary effect on attention, dose-response curves for ethanol were determined in eight pigeons trained under a titrating matching-to-sample (TMTS) procedure, in eight pigeons trained under a discrete-trial measure of attention, and in eight pigeons trained under a continuous-trial measure of attention. Ethanol decreased accuracy under the TMTS procedure following the three highest doses (1, 1.8, and 3 g/kg). Only the highest dose (3 mg/kg) decreased rates of responding. Attention, as measured under the discrete-trial procedure, was affected only by the two highest doses (1.8 and 3 g/kg). The 3-g/kg dose caused significant decreases in the probability of a hit and probability of a correct rejection, as well as significant increases in the probability of an error of omission and response latencies. Sensitivity to the signal decreased following 1.8 and 3 g/kg ethanol. Under the continuous-trial procedure, ethanol caused a peak in false alarms after the 1.8-g/kg dose, decreased the probability of a hit following the 1.8- and 3-g/kg doses, and increased probability of a miss at all doses. Sensitivity to the signal was not affected. A comparison of the dose-response curves for the TMTS procedure and the two measures of attention revealed that working memory (TMTS) was decreased by a lower dose than that affecting attention. This suggests that the effects of ethanol on working memory are not mediated by the subject's ability to pay attention to stimulus changes in the environment.