When Hall and his colleagues watched the subjects' brains in action, they got some interesting results. As reported in the April issue of the journal Psychological Science, the subjects who were most impulsive and antisocial had EEGs that were quite different from those who were low on these traits. Specifically, the electrical pulse associated with error monitoring was much lower in this group, and it was lower immediately after the subjects erred on a test item, suggesting that the brain's normal response to making mistakes was malfunctioning.

Scientists have not worked out all the neurology yet, but one theory about this electrical pulse is that it is somehow sending messages to several distinct brain regions, perhaps through the neurotransmitter dopamine. These structures, in turn, are responsible not only for monitoring and correcting immediate errors but also for enhancing cognitive control long term. Or not, depending on the potency of the signal. It appears that those with a sputtering electrical generator just keep making the same mental and emotional slips again and again.

All of the subjects in this experiment were healthy university students. This is important because it means that even those at the extremes of the impulsivity scale were in the normal range. None were in jail, for example, and it's unlikely many are heading there. But those with this early antisocial bent could well be heading toward some difficulties in life. Other EEG studies have linked the same weakened electrical pulse to a deficit in such traits as sense of duty, responsibility and reliability. Such personality deficits may not be pathological, but they reflect a lack of conscientiousness about detail that makes for less than ideal workers, spouses and citizens. To quote the great American psychologist Poor Richard: "A little neglect may breed great mischief."

Wray Herbert writes the "We're Only Human . . ." blog.

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