After four vodka tonics, you might feel determined to conquer fear and finally tell your married co-worker that you've been in love with her for years. But the next morning, not so much.

It may seem obvious to most of us that drunken promises don't mean much, but apparently two German researchers weren't so sure. Using 60 undergrads as guinea pigs, they designed a randomized control trial to test the effects of alcohol on a person's commitment to unrealistic goals.

"People may indicate being determined to reach their goals after having consumed alcohol," wrote the researchers in the August edition of the Journal of Abnormal Psychology, "but once sober again, they do not walk the talk."

After asking participants about their most-important personal goals, the researchers gave half the students vodka tonics and the other half plain tonic water with lime. To separate the true effects of alcohol from the psychological effects of thinking you're intoxicated, the researchers went to great lengths to convince the entire group that they'd be sipping spirits, including sneakily smearing all the glasses with alcohol and pouring decarbonated tonic water out of a vodka bottle.

They must have done a pretty good job, as only two people from the placebo group realized they'd been duped (and one tolerant drinker in the vodka group thought he'd been tricked, too).

After four drinks, both groups were asked to rate their commitment level to a specific goal. Not surprisingly, inebriated students expressed strong commitment to their deepest desires, whether it was to hook up with a new friend or fly to France to visit a relative. But unlike sober participants, the drinking group didn't lower their commitment level just because a goal was unrealistic.

"Intoxicated participants' lack of considering their expectations particularly played out when chances to attain the goals were grim," wrote researchers. "In light of low expectations, participants in the alcohol condition felt more committed to their goals than did participants in the placebo condition, whereas in light of high expectations, commitment did not differ between conditions."

In other words, drunk people ignore reality and think they can do just about anything, a condition scientists have aptly labeled "alcohol myopia."

Unfortunately, drunken courage didn't translate into sober certitude. In a second, similar study, the researchers followed participants for three weeks after the experiment. Among the sober crew, the strength of a person's commitment predicted how many steps they would take to achieve their goal in the following weeks. But among those who had been drinking, commitment didn't correlate with future action.

The researchers say their results can help explain why people who don't have high hopes for success are more likely to abuse alcohol. The study also helps clarify why weekend revelry never leads to dogged concentration on Monday morning. Or maybe that's the hangover.

Via Mind Hacks.

Image 1: Flickr/Jeremy Brooks. Image 2: Figure 1 from Sevincer and Oettingen, "Alcohol Breeds Empty Goal Commitments," Journal of Abnormal Psychology, Vol. 188 (3), 623-633, August 2009. Reprinted with permission from the American Psychological Association.

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