Search Here

Alcohol, especially when consumed in excess, can hinder people's cognitive functions. Researchers in a new study set out to determine just how much alcohol can impair vision. By using a 144-year-old optical illusion, the researchers from the Schulich School of Medicine and Dentistry and the Faculty of Social Science in Canada concluded that the legal limit of alcohol could hinder vision by 30 percent.

"We obviously know alcohol impairs our decision making and motor skills but until now, we did not know how alcohol affects our vision," said researcher Kevin Johnston, a research scientist at the Department of Physiology and Pharmacology's Laboratory for Neural Circuits and Behavior. "What we have done now, using century-old methods, is find out exactly how much vision is impaired after drinking alcohol."

Johnston and Brian Timney utilized the Hermann Grid, which was created by Ludimar Hermann in 1870. The grid acts as an optical illusion that can measure people's perception of contrast. The grid has black squares on top of a white surface. The researchers tested people's ability to see the contrast between the black and white colors. People should be able to see the gray circles at the intersections due to the effect of the optical illusion.

The researchers found that people who had consumed alcohol were less likely to see the contrast of the ghost-like circles. The team calculated that people who had the legal blood alcohol level had impaired vision by 30 percent. The researchers concluded that drinking could affect people's ability to drive during twilight hours.

"This is obviously important when you are driving at twilight, when objects are more difficult to see and more difficult to discriminate, even without alcohol," Timney said reported by the school's news release. "It's at those times when you are going to be most affected, and impaired."

The study was published in Perception.