The combined effects of alcohol consumption and cigarette smoking on critical flicker frequency.

Previous studies have found that subjects report a raised critical flicker frequency (CFF) threshold after smoking a cigarette and a lowered CFF after drinking a moderate dose of alcohol. The present aim was to examine the joint effects of these two drugs on CFF. Although the changes in CFF were in the expected direction for each drug separately, the combined effects were variable, depending in part on the type of test being used. In a lengthy signal detection task (Experiment I), combining the drugs resulted in antagonism, but with short probe tests (Experiments II and III), the smokers showed little effect for alcohol alone, but decreased thresholds if they were allowed to smoke at the same time. Experiment IV examined the effects of both drugs on long and short threshold tests within the same session, essentially confirming the previous findings. Additional pre-drug threshold differences were found between smokers who were required to refrain from smoking overnight before testing and those who were nondeprived.