Although many studies have shown that people given a placebo will often behave as if drunk, this doesn't prove that the effect of alcohol is purely psychologica

Although many studies have shown that people given a placebo will often behave as if drunk, this doesn't prove that the effect of alcohol is purely psychological. Although people will begin to behave as if drunk, my understanding is they will tend to behave in a manner which they would normally feel slightly inhibited from. When someone has actually consumed alcohol they will be more likely to perform actions which there is a high (rather than medium as with the placebos) social pressure against. I can see the coffee example working for both consciously using alcohol as an excuse for socially unacceptable behaviour and the type of results seen when placebos are given but not the more extreme responses associated with higher intakes. Old paper but a good one is The Psychology of Drunken Excess (http://psycnet.apa.org/journals/psp/48/1/18/ http://psycnet.apa.org/journals/psp/48/1/18/) but afraid I don't think it's available without paying.