Neuroscience
Forget shifty eyes or fidgety fingers, psychology research has shown that these supposed signs of lying are unreliable. Liars easily learn to make eye contact, and anxiety can make honest people squirm nervously.
A more useful foundation for lie-detection is the simple fact that lying is more cognitively demanding than telling the truth. False answers therefore usually take slightly longer than honest responses, especially when a suspect is burdened with an extra mental challenge, such as telling their story backwards.
However, a new study suggests that the cognitive demands of lying can be reduced with practice. Xiaoqing Hu and his team presented 48 participants with dates, place names and other information and asked them to indicate with one of two button presses whether the information was self-relevant or not. In real life this would be equivalent to a suspect posing as a different person. Instructed to lie, the participants took longer to respond than when they told the truth, consistent with the well-established idea that lying is cognitively demanding.
Next, a third of the participants were told about the reaction time difference and given extensive practice (360 trials) at lying more quickly about the self-relevance of information. The requirement to get faster was made explicit because past research found lying practice without such an instruction was ineffective. On retesting, the trained participants in the current study no longer took more time to answer dishonestly compared with telling the truth. "Deception is malleable and its performance index can be voluntarily controlled to be more automatic," the researchers said.
Another group had no training but were told about the reaction time difference between lying and truth telling, and encouraged to answer faster when lying. They got faster at lying compared with a control group, but still they were speedier when being honest.
The researchers admitted that their sample size was small and a replication is needed with more participants. However, they said their results suggest that to be more realistic, lie-detection research based around the cognitive demands of lying should incorporate the effects of practice.
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Hu, X., Chen, H., and Fu, G. (2012). A Repeated Lie Becomes a Truth? The Effect of Intentional Control and Training on Deception. Frontiers in Psychology, 3 DOI: 10.3389/fpsyg.2012.00488
Also published recently: Sorting the Liars from the Truth Tellers: The Benefits of Asking Unanticipated Questions on Lie Detection.
Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.
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Neuroscience
Lying becomes automatic with practice
A more useful foundation for lie-detection is the simple fact that lying is more cognitively demanding than telling the truth. False answers therefore usually take slightly longer than honest responses, especially when a suspect is burdened with an extra mental challenge, such as telling their story backwards.
However, a new study suggests that the cognitive demands of lying can be reduced with practice. Xiaoqing Hu and his team presented 48 participants with dates, place names and other information and asked them to indicate with one of two button presses whether the information was self-relevant or not. In real life this would be equivalent to a suspect posing as a different person. Instructed to lie, the participants took longer to respond than when they told the truth, consistent with the well-established idea that lying is cognitively demanding.
Next, a third of the participants were told about the reaction time difference and given extensive practice (360 trials) at lying more quickly about the self-relevance of information. The requirement to get faster was made explicit because past research found lying practice without such an instruction was ineffective. On retesting, the trained participants in the current study no longer took more time to answer dishonestly compared with telling the truth. "Deception is malleable and its performance index can be voluntarily controlled to be more automatic," the researchers said.
Another group had no training but were told about the reaction time difference between lying and truth telling, and encouraged to answer faster when lying. They got faster at lying compared with a control group, but still they were speedier when being honest.
The researchers admitted that their sample size was small and a replication is needed with more participants. However, they said their results suggest that to be more realistic, lie-detection research based around the cognitive demands of lying should incorporate the effects of practice.
_________________________________
Hu, X., Chen, H., and Fu, G. (2012). A Repeated Lie Becomes a Truth? The Effect of Intentional Control and Training on Deception. Frontiers in Psychology, 3 DOI: 10.3389/fpsyg.2012.00488
Also published recently: Sorting the Liars from the Truth Tellers: The Benefits of Asking Unanticipated Questions on Lie Detection.
Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.
- Teenage Offenders Are Highly Adept At Spotting When Their Peers Are Lying
Most people are poor at detecting whether someone is lying, at least partly because most people think mistakenly that things like shifty eye movements and fidgeting hands are reliable signs of deception. However, it's emerged in recent years that...
- How To Cheat A Brain-scan-based Lie Detector
Cheating the scanner is relatively easySure, it's possible to differentiate patterns of truth-telling brain activity from patterns of lying-related activity. But contrary to media hype, experts have been quick to point out that the accuracy of brain-scan...
- Shock Result! Asking Children And Teenagers To Promise To Tell The Truth Actually Works
When teenagers are asked to provide testimonies for use in court, how do you increase the likelihood that they'll tell the truth? It may sound twee, but a North American study claims that merely asking them to promise to tell the truth can be surprisingly...
- The Latest Verdict On Using Brain Imaging For Lie Detection
Excitable tabloids, technophile lawyers and gullible entrepreneurs have all spent the last few years salivating over the prospect of functional brain imaging delivering us the first form of truly scientific, objective lie detection. Not so fast. Most...
- Truth-telling And The Brain
Can brain-imaging technologies show whether we are being truthful or not? A current study, reported by Reuters (as found on the Houston Chronicle website), takes a look:Brain scans can tell who's lying, who's not Reuters News Service Nov. 29,...