Alcohol Impairment Overrides Impulse Control
Researchers at Ontario’s Western University Brain and Mind Institute are reporting a study that shows how alcohol interferes with a normal brain mechanism – the ability to put the brakes on a bad decision.
We all make snap judgements or act on impulses. But having an impulse and acting on it are not the same thing. Generally, there’s an evaluation step – a chance for our higher mind to block poor decisions before we continue on and make a serious mistake. It’s this step that alcohol seems to be blocking. When drunk, we aren’t more impulsive, we just don’t override our impulses as well.
Studying this mechanism with a simple task
In the press release, the experiment is described as a pointing task, taken both while sober and then again at the legal limit for driving.
The target predominantly remained stationary, but sometimes it abruptly jumped to a new location. Previous studies have shown that people quickly and accurately self-correct for such target jumps and that an "autopilot"-type mechanism in the brain underlies this rapid and automatic response.
Participants in this study generated similar results both sober and after a few drinks but that all changed dramatically when participants were asked to simply stop their movements when the target jumped.
The new task required subjects to override an impulse to point, and after drinking, they had a difficult time doing so. It seems simple enough: Point at the target when it appears, but don’t point if it jumps around. The simplicity is key to the experiment. Participants were unable to turn off their “autopilot.”
This makes a great deal of sense to those who are familiar with drunks. So long as they are able to follow a habitual pattern, they do fine. But as soon as a surprise intrudes, they seem unable to react appropriately, especially if the change goes contrary to their habitual action.
As researchers put it, “Things go well for practiced or automatic behaviors, but really fall apart when you have to override these responses and to something different.”
Applying this mechanism to drunk driving
The same mechanism is in play for drunk driving. Driving is a habitual, familiar activity. With moderate amounts of alcohol, and barring any surprises, a drunk driver may make it home. But any deviation from the routine, such as a pedestrian walking into the road or another car stopping suddenly, and they can’t compensate.