The findings showed that the brain's "alarm signal" in response to errors was much less pronounced in those who had consumed alcohol, and the response was the largest for those in the placebo group.
http://www.ummid.com/news/2011/September/04.09.2011/alcohol_dulls_brain.htm
http://www.ummid.com/news/2011/September/04.09.2011/alcohol_dulls_brain.htm