Deception detection: how to tell if someone is lying

During high-stake police interrogations and on seemingly meaningless online dating profiles, some people find themselves lying. So, how can you tell if someone isn't telling you the truth?

There is no single 'Pinocchio's nose,' forensic psychology expert says

Scientists seem to agree that some cues exist to help spot potential liars, but no one sign is particularly strong on its own.

The unfolding tale of a 12-year old Detroit boy who was found in his basement following an 11-day search after he was reported missing by his father and stepmother has investigators searching for the truth.

This week, Michigan's child-welfare agency filed detailed allegations of physical and mental abuse in an attempt to revoke the parental rights of Charlie Bothuell IV's parents.

Before police discovered the boy in the family's basement, Charlie's father pleaded on TV for his son's safe return. But, the boy claims his stepmother ordered him to stay in the basement.

Now, police must work to unravel the truth.

Is there any way to catch a lie either during a high-stake police interrogation or on a seemingly meaningless dating profile?

"There is no one 'Pinocchio's nose,'" said Stephen Porter, a University of British Columbia psychology professor and registered forensic psychologist, in an email interview with the CBC.

Experts studying the art of deception train professionals how to tell if someone isn't telling the truth. Porter's research team studied detecting lies in high-stakes deception, focusing on people who make public pleas for the return of a missing relative and are later charged with their murder.

Porter and other scientists agree that cues exist to help spot liars, though these tend to differ based on how much is at stake for the liar.

None of the so-called signs are very reliable on their own, warns Porter.

"Rather than looking for the holy grail of lie detection, it seems that a comprehensive approach that examines the content, body language and facial expressions of potential liars is most effective," says Julia Shaw, from a research conference in Russia, in an email interview.

Shaw, a professor with her PhD in forensic psychology, researched the effectiveness of training professionals to be human lie detectors along with Porter and another colleague.

See the infographic below for tips and tricks from the pros on how to spot a liar:

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(Duk Han Lee/CBC)

It's increasingly difficult to tell if someone is lying if you're engaging in a conversation with them, says David Skillicorn, a professor at Queen's University school of computing.

In a conversation, the common signals of lying become muddled because the other person's words have a strong influence on the liar, he explains. People tend to mimic the language of those they are speaking to.

Skillicorn studied deception detection in text, like political speeches, where he says the process "becomes a whole lot easier."

In written statements, four patterns emerge when someone is being deceitful:

  • First person singular pronouns decrease.
  • Negative emotion words, like hate, increase.
  • Action verbs increase.
  • Exclusive words, such as but and or, decrease.

Skillicorn used those patterns to analyze U.S. presidential candidate speeches during the 2012 election.

But he says it's much harder to recognize those patterns in a conversation.

"It's really hard to turn this into something that you can use face-to-face because we just aren't equipped right," he says. Humans don't have the right hardware to keep track of all these things during a conversation, which is already muddled by the influence of their words and actions.

"That's the annoying part, right?" he says, admitting he can only keep track of the patterns for about two sentences before he becomes confused. "You can't get an app to stick in your brain that will do this for you."

With files from The Associated Press