You may blame your scandalous behavior with our best friend's spouse at the party last night on the booze. But Alan Lang knows better. Lang, an assistant professor of psychology at Florida State University, conducted a study of college students to find out whether alcohol really dissolves sexual inhibitions, or if it just provides a good excuse. He found that straight tonic water worked just as well as vodka and tonic in producing sexual lubricity -- as long as the students thought they were drinking the real thing. If they thought they were drinking only tonic water, they felt sober, even if the drinks were really spiked. His conclusion: alcohol's pharmacological effects do not matter nearly so much as what the drinker expects, consciously or not, that booze will do for him. The study also found that men with the greatest sexual inhibitions were most affected by alcohol. Lang divided 72 college men into four experimental groups: two who received either vodka and tonic or straight tonic and were told the truth about what they were getting, and two others who also got spiked or unspiked drinks but were lied to about the contents. Of the 36 men who were deceived, only five correctly guessed the contents of their drinks. Fifteen minutes after downing their drinks, the subject sat at a desk and viewed slides projected on a wall. They were asked to grade each slide by artistic merit, sexual stimulation and pornographic content. The 20 randomly arranged slides varied from showing females fully clothed or partly clothed to showing nude heterosexual couples in explicit sex acts. All the subjects who believed they had drunk alcohol -- whether or not they really had -- rated the slides as much more sexually stimulating than those who thought they were drinking only tonic. But the men with high sex guilt -- as measured by a separate psychologica test -- showed more noticeable effects if they thought they were getting booze: they lingered longer on each slide, particularly the X-rated slides, than high-guilt men who thought they were drinking straight tonic. "The effects of drinking on socially relevant behaviors in men may be largely a function of expectancy rather than physiology, at least where low to moderate doses of ethanol alcohol are concerned," Lang and his colleagues concluded.