U.S. researchers say with a certain amount of training and instruction a person could learn to tell a lie that may be indistinguishable from the truth. The study at Northwestern University, which suggests the art of deception can be perfected, has implications for law enforcement and the administering of lie detector tests, a university release said Thursday. Previous researchers has shown most people take longer to respond and make more mistakes when telling lies than telling the truth because they have to hold two conflicting answers in mind and have to work to suppress the honest response, the researchers said. The Northwestern study looked at whether people could train themselves to make telling a lie more automatic and avoid the tell-tale signs. Reaction times associated with study participants\' deceptive responses could be significantly lowered with some practice, they found. \"We found that lying is more malleable and can be changed upon intentional practice,\" lead author Xiaoqing Hu, a psychology doctoral candidate, said. Participants in previous research into lying were given very little time to prepare their lies, he said. \"In real life, there\'s usually a time delay between the crime and interrogation,\" Hu said. \"Most people would have time to prepare and practice their lies prior to the interrogation.\"