Picture this: You are in a bar. You have been drinking beer for a few hours. One turned into two turned into five. In a drunken state you leave, and you begin to stumble home. On the way home you witness a violent assault. You immediately call the police and tell them what you remember.

Every day, people find themselves in exactly this kind of situation. Crimes are often committed by drunk people, against drunk people, in front of drunk people. This is particularly true of violent crimes. When we try to solve these cases and hold perpetrators accountable, the accounts of those involved might be the only evidence available. But can we trust these memories?

Lauren Monds is a postdoctoral researcher in addiction medicine at the University of Sydney, Australia. Her work focuses on understanding how people who use substances think and behave. She also has a background in researching false memories for distressing events. This puts her in an ideal position to tell us whether drunk people can have reliable memories.

Better than we think?

According to Monds “We already know that our memories are not perfect; flawed eyewitness memory is one of the key reasons for wrongful convictions. We also know that different substances (e.g., alcohol, illicit substances, and certain medications) can potentially impair memory”.

So, how exactly does alcohol impact eyewitness memory? Most experimental research (like this study and this study and this study) has found that intoxicated eyewitnesses are actually no different from sober eyewitnesses in their account accuracy or vulnerability to distortions. One study published this year even found that consuming alcohol after witnessing a crime made witnesses more reliable, by making them less likely to accept false details given to them by the researcher.

However, Monds argues that this research should be taken with caution “While there have been several lab studies where people are given alcohol and then their memory is tested, this generally involves low levels of alcohol”. In other words, participants in research studies might not be as drunk as people who walk out of bars after five whiskey sours and witness actual crimes. She argues that this means, “we don’t actually know how much (or even in some cases, if) intoxication impairs eyewitness memory for an event.”

Hello, Occifer…

So, what’s a cop to do? Monds says that police often have guidelines about how they should treat people who have been drinking; “Generally, police interviewing procedures preclude interviewing intoxicated witnesses.” She says that this is problematic because on top of the issue that intoxicated witnesses may not actually be so bad, such guidelines also involve the assumption that a police officer can spot whether someone is drunk (or otherwise intoxicated) without doing any actual drug testing.

Seems easy enough. Slurring words, stumbling about, perhaps some random giggling. These are the kinds of behaviors we might see in some cases, but they are by no means universal. Perhaps like me, you have a few friends who can act far more sober than their alcohol consumption warrants. This begs the question; what does a drunk person look like?

Monds points out that there is almost no research on whether people can tell that others have been drinking. This is part of what her next line of work on intoxication detection will look at; “I am hoping that my research will contribute in two main ways; to help determine what (if any) cues to intoxication are useful, and to help work out how memory is impaired for events when under the influence."

The take-home message seems to be that witnesses who are suspected of being intoxicated should still be taken seriously. Additionally, people who are slightly or moderately drunk should be interviewed immediately after witnessing a crime, rather than after they have sobered up (according to this study).

Don’t let a few drinks stop you from giving a witness statement. An intoxicated witness can still be a good witness.