Deception can be perfected: Can a repeated lie become 'a truth? '

People generally take longer and make more mistakes when telling lies than telling the truth, because they are holding two conflicting answers in mind and suppressing the honest response, previous research has shown. Consequently, researchers in the present study investigated whether lying can be trained to be more automatic and less task demanding.

This research could have implications for law enforcement and the administering of lie detector tests to better handle deceptions in more realistic scenarios.

Researchers found that instruction alone significantly reduced reaction times associated with participants' deceptive responses.

They used a control group -- an instruction group in which participants were told to speed up their lies and make fewer errors, but were not given time to prepare their lies -- and a training group, which received training in how to speed up their deceptive responses and were given time to prepare their lies. In the training group that practiced their lies, the differences between deceptive and truthful responses were completely eliminated.

"We found that lying is more malleable and can be changed upon intentional practice," said Xiaoqing Hu, lead author of the study and a doctoral candidate in the department of psychology at Northwestern.

Hu said they were surprised that even in the instruction group, members who were not given time to prepare their lies and told only to try to speed up their responses and make fewer errors were able to significantly reduce their deceptive response reaction time.

"This was really unexpected because it suggests that people can be really flexible, and after they know what is expected from them, they want to avoid being detected," Hu said, noting the findings could help in crime fighting.

"In real life, there's usually a time delay between the crime and interrogation," said Hu. "Most people would have time to prepare and practice their lies prior to the interrogation." However, previous research in deception usually gave participants very little time to prepare their lies.

Lie detector tests most often rely on physiological responses. Therefore, Hu said further research warrants looking at whether additional training could result in physiological changes in addition to inducing behavior changes as observed in their study.