"Another aspect of personality that has been studied is inhibition. It has been suggested that inhibition discourages risk-taking, which is necessary for progress in language learning. This is often considered to be a particular problem for adolescents, who are more self-conscious that younger learners. In a series of studies, Alexander Guiora and his colleagues (1972) found support for the claim that inhibition is a negative force, at least for second language pronunciation performance. One study involved an analysis of the effects of small doses of alcohol, known for its ability to reduce inhibition, on pronunciation. Study participants who drank small amounts of alcohol did better on pronunciation tests than those who did not drink any. While results such as these are interesting, they may have more to do with performance than with learning. We may also note, in passing, that when larger doses of alcohol were administered, pronunciation rapidly deteriorated!"
I can think of a few people who probably would have been willing to participate in that study and contribute to scientific knowledge. ~Abu Tulip