Detecting Deception: Non-Verbal Cues or a Product of Trauma? | Sarah MacDonald | TEDxUAlberta

[Music] when my husband meets new friends and colleagues for the first time and they ask about me and what I do he will often tell them that I do research and detecting lies and that I train the police how to interrogate people now over the last five or six years no matter how many times I say it's not interrogation it's called investigative interviewing the word interrogation still sticks now the response from these new friends and colleagues is almost always something along the lines of well you must not be able to get away with anything now I don't want to drag down the festive and the upbeat spirit of TEDx especially right off the bat but I'm afraid to tell you that this whole room is full of a bunch of liars we all lie at least once or twice a day in fact research has shown that 60% of adults cannot have one conversation without lying at least once this means that in one day you could be lied to up to 200 times we lie most frequently about our thoughts our feelings our attitudes and our preferences sometimes we lie to influence how other people perceive us to save face or to just avoid hurting someone's feelings lies even oil the wheels of social interaction now not to pick on my husband again but tomorrow he might tell me that my talk today was the most interesting most engaging speech he's ever heard but if this is untrue and he was actually bored to tears I might not really want to know that but people lie for much more serious reasons as well such as to hide transgressions these lies like denying involvement in criminal activity can have very serious consequence is for the liar if they're discovered now as psychologists we call these high-stakes lies and we've been interested in detecting this kind of insidious deception for decades there's this underlying assumption that the act of being deceptive produces this physiological change compared with telling the truth the theoretical argument is that lying is more difficult so it's very cognitively demanding it produces arousal meaning that the liar experiences feelings like guilt fear and excitement and the liar may attempt to control his or her behavior in order to appear credible so it's these three factors that are argued to lead to the differences in the way that we speak and the way in which we behave when we're telling a lie now I bet you all think you have a pretty good idea of what a liar looks like right fidgety avoiding eye contact maybe nervously tapping a pen or shaking one's foot what about when someone is nodding their head yes but saying something along the lines of well I didn't have a sexual relationship with that person are these behaviors indicators of deception well if you think that they are and I can see some heads nodding then you're certainly not alone seventy-two percent of people worldwide think that avoiding eye contact is the most presumed sign of lying but it turns out that there are actually very few behavioral cues associated with lying research tells us that there's really only three nodding foot in leg movements and illustrator use so just using our hands to supplement whatever it is that we're saying the most reliable verbal cue is voiced pitch studies tell us that Liars tend to speak in a higher pitched voice compared to truth tellers but despite what the research tells us that there's few behavioral cues related to deception professionals all over the world truly believe that nonverbal behavior and emotional expressions are directly related to someone's truthfulness now let's take an extremely consequential situation where lie detection gets played out in a very high stakes context so part of my job is to conduct forensic interviews with victims of sexual assault so police detectives will ask me to conduct an interview for their file for a variety of different reasons my goal is to obtain as much accurate information as possible and to find out the truth of what happened so that the investigation has the best chance of success so when a victim tells me about being horrifically assaulted but she's doing so with a smile on her face does that mean that she's lying what about when a victim is telling me about being assaulted by someone that she knows and trusts but she can't recall certain details details that I think are really important and ones that maybe anybody would remember but she can't does that mean that she's making it up and that she's lying what about when someone is recalling a gruesome crime but showing no mo expression so they're recalling the event with a completely flat effect are they lying the answer to all of the above is no people who have gone through a traumatic event often do not react the same way that they would in a normal situation the problem is that this can often appear to be deceitful trauma changes the way that our brain works the part of our brain that is responsible for decision-making judgment and executive functioning known as the prefrontal cortex is often completely impaired the part of our brain responsible for language production known as the Broca's area is also often impaired the hippocampus which is responsible for transferring short-term memories into long-term memory is also not working properly so to me and my law enforcement colleagues who really understand memory many of the seemingly deceptive behaviors actually make sense and we understand them as a product of trauma but to others who maybe don't have a comprehensive knowledge of how trauma affects the brain these behaviors might look like lying a victim who laughs while telling me about her his or her assault well this can be explained by using what we know about neuroscience I understand why a victim might be able to recall every single detail about a particular smell or being able to tell me that there were exactly 17 tiles in the ceiling but at the same time can't give me any information about what the perpetrator looked like during trauma your brain has zero ability to control what it pays attention to our memory does not work like a video recorder there's no rhyme or reason to what gets encoded into our memory and what doesn't traumatic events are often able to be recalled a very sensory level meaning that things like tastes smells and sounds might be able to be recalled in amazing detail but perhaps information like visual details well that could be a struggle trauma and memory are complex and the behavioral outputs often present much like behaviors that are thought to be associated with lying the problem though is that at many different stages at the criminal justice system all over the world victims credibility is being assessed based on behaviors that are not supported by science and what does this mean well at the end of the day it could mean that once a case goes to trial a judge and our jury relies on behaviors to determine the victims credibility and decides that they're not believable and then in turn the perpetrator is never convicted even if he or she is actually guilty so please be very cautious in your endeavors to detect lies do not believe what you see on TV critically question the glossy commercialized articles that you see all over the internet promising you top tips on how to become a human lie detector verbal and nonverbal behavior should not be used in isolation to determine someone's credibility but perhaps could be used as a tool to identify topics that need to be probed and investigated further there is indeed no Pinocchio's nose thank you [Applause] [Music]

Channel: TEDx Talks

Views: 22,398

Keywords: TEDxTalks, English, Canada, Social Science, Behavior, Body language, Communication, Law, Psychology, Sexual Assault, Truth

Id: aYSqN_f2RSk

Length: 10min 2sec (602 seconds)

Published: Fri Jul 21 2017