We all know that one friend who is the 'fun drunk' and life of the party after she has had one drink too many, or that lovely fellow in Accounting who becomes downright nasty once he gets in his cups.

Except that we don't.

Researchers from the University of Missouri, St. Louis – Missouri Institute of Mental Health did a study of the “drunk personality” and learned that our drunken personas were not significantly different from our sober selves, even when we think that they are.

"We were surprised to find such a discrepancy between drinkers' perceptions of their own alcohol-induced personalities and how observers perceived them," said lead researcher Rachel Winograd.

Winograd's team assessed and categorized the personality traits of 156 people, first stone sober, and later when they were legally drunk. The researchers hoped to carefully calibrate alcohol consumption and closely monitor individual behavior.

Over the course of about 15 minutes, each participant in the study drank either Sprite or individually-tailored vodka and Sprite cocktails designed to produce a blood alcohol content of about .09. After being allowing some time for their systems to absorb the alcohol, the participants were put through paces intended to play up a variety of personality traits and behaviors.

The study participants completed personality measures at two points during the laboratory period, while outside observers used video recordings to complete standardized assessments of each individual’s personality traits.

The researchers found that only “extraversion” was perceived to be different across participants in alcohol and sober conditions. Since that is the most outwardly visible personality factor, the researchers calculated that it makes sense both the participants and researchers saw differences in this trait.

"We believe both the participants and raters were both accurate and inaccurate – the raters reliably reported what was visible to them and the participants experienced internal changes that were real to them but imperceptible to observers," Winograd explained.

Is it possible that all those white lab coats and chrome fixtures may have had a... dampening effect on the study participants' mood?

"Of course, we also would love to see these findings replicated outside of the lab – in bars, at parties and in homes where people actually do their drinking," Winograd said. “Most importantly, we need to see how this work is most relevant in the clinical realm and can be effectively included in interventions to help reduce any negative impact of alcohol on peoples’ lives.”

The study was published in the journal Clinical Psychological Science.