Drinkers compensate for alcohol impairment by seeking cues in their immediate environment that signal how to behave, finds a study in the March issue of APA's Experimental and Clinical Psychopharmacology (Vol. 13, No. 1).
In the study, University of Kentucky psychology professor Mark Fillmore, PhD, and postdoctoral fellow Cecile Marczinski, PhD, had 24 adult volunteers view a computer monitor containing a white rectangle positioned upright or on its side. After a few moments, the rectangle changed color. Horizontal rectangles were likely to turn green, and vertical rectangles to turn blue.
The researchers randomly split the participants into two groups. For one group, the rectangle's orientation correctly predicted its color 60 percent of the time; for the other, orientation correctly predicted color 80 percent of the time. Participants learned the orientation-color relationship during a 35-minute pretest.
All participants performed a 500-trial test three times: once sober (after drinking a placebo), once after drinking the equivalent of about three drinks and once after about five drinks.
Fillmore and Marczinski found that drunken participants in the 80-percent accurate condition frequently erred when the rectangle's orientation was misleading (which occurred once every five trials). Most of the time, they incorrectly pressed the keyboard when a blue rectangle followed a horizontal rectangle and took longer to press the keyboard when a green rectangle followed a vertical rectangle. The alcohol prevented participants from processing the conflicting information, Fillmore conjectures, so they compensated by relying on the associations they first learned about the rectangles, which in every fifth case were wrong, Fillmore says.
Meanwhile, participants in the 60-percent accurate condition made roughly half as many mistakes. The results suggest that even a small amount of alcohol makes people more dependent on the environment for clues about how to behave. For example, they're more apt to unconsciously gun a car at a green light--but only when that environment is familiar and predictable.
Such dependency can cause problems in practical situations like driving, Fillmore says.
"If someone who was drinking began driving on a familiar route, they'd pay less attention to their behavior and the specific situations on the road. They wouldn't be prepared for anything new, like construction," he says, noting that in these situations, drivers, for example, may speed through green lights even if the intersection is not clear. "Alcohol makes an individual more likely to rely on habit and let the environment around them dictate how they do things."