It sounds like alcohol improved their automated, instantaneous processing - or in other words, System 1 thinking. Based on what I know about alcohol, I'd guess it still slows down your System 2 thinking considerably. In fact, that could even be an explanation for the improvement in System 1 speed: their fact-checker is disabled, so they answer with their intuition right away.
saw this on reddit. Thought people here would be interested.
http://medicaldaily.com/news/20120411/9496/alcohol-solving-skills-analytical-thinking-creativity-study.htm
edit: from a comment in the reddit thread
http://www.reddit.com/r/science/comments/s50la/drinking_alcohol_may_significantly_enhance/
"The article is here for those who are interested. Going through the article, the measure they chose was the Remote Associates Test. In this test you are given 3 words like ARM, TAR, and PEACH and supposed to guess the associated word. (PIT in this case) (more here if you want to give it a shot). The three words flash on the screen and you are given 1 minute. When you 'know' the answer you press a key and write in your answer. The time to press the key and whether the answer was right are recorded. Afterward you are told to say how you came to the answer on a scale of 1-7 (1 being strategy 7 being a flash of insight). Drunk (
.7.07 (thanks Erobre) BAC) people answered slightly faster and came to 20% more solutions. (they also said their answers were based more on insight than strategy)"The "here" links to http://www.sciencedirect.com/science/article/pii/S1053810012000037