How Drinking Can Increase Perceptual Blindness

By Beth Leipholtz 03/05/18

A new study explored how alcohol consumption can impact our ability to see something unusual unfold right in front of us.

Woman drinking alcohol on dark background

A new study claims that consuming alcohol could increase the likelihood of failing to notice obvious objects—a phenomenon known as inattentional blindness. 

According to Scholarpedia, inattentional blindness (also known as perceptual blindness) is “the failure to notice a fully-visible, but unexpected object because attention was engaged on another task, event, or object.” 

“Being intoxicated—even to within the legal driving limit—will significantly reduce your likelihood of noticing a novel or unusual event unfold right in front of you, if you happen to be engaged in some simple but on-going task,” said study author Alistair J. Harvey of the University of Portsmouth, according to PsyPost

The term first emerged in 1999, after a study referred to as the invisible gorilla experiment. In the study, people were asked to watch a video of a group playing basketball and count how many times the ball was passed. As they were doing so, a man in a gorilla suit walked into the scene, beat his chest, and walked away. But only a small percentage of the participants noticed this. 

In the new study, Harvey and his colleagues found 104 participants from a university’s student bar and used a breathalyzer to measure their intoxication level. Like in the original invisible gorilla experiment, the participants were asked to watch the basketball video and count the passes, then asked if they had noticed anything unusual. 

According to PsyPost, the study found that alcohol intoxication increased inattentional blindness when the participants had to count the number of passes. However, it did not increase inattentional blindness when they were asked to count the number of aerial and bounce passes. 

“If we drink sufficient alcohol and are engrossed in some on-going activity we are significantly less likely to notice what’s going on around us than when sober,” Harvey told PsyPost. “This is because alcohol reduces our cognitive reserves, forcing the brain to allocate its dwindling mental resources to only the most important tasks at hand.”

“However, our study reveals that alcohol does not impair peripheral attention when we are absorbed by a particularly demanding task and we think this is because hard tasks leave little to no mental capacity leftover for alcohol to deplete.”

According to Harvey, this study had some limitations. 

“Although our study shows significant effects of attentional narrowing at blood alcohol levels lower than this country’s legal driving limit, it is restricted to a simple situation in which the viewer’s attentional focus is engaged by only a single visual tracking task,” he told PsyPost. “Our findings cannot be generalized to more complex activities, such as driving, where the viewer must attend to an array of important visual stimuli.”

This study was published in the journal Psychopharmacology.  

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Beth is a Minnesota girl who got sober at age 20. By day she is a website designer, and in her spare time she enjoys writing about recovery at, doing graphic design and spending time with her boyfriend and three dogs. Find Beth on LinkedInInstagram and Twitter.