Generally, it takes longer to tell a lie than to tell the truth.
Most people find it easier to lie in a foreign language than in their native tongue, according to a study.
The findings, published in the Journal of Experimental Psychology, could be important for a lot of processes in which the trustworthiness of certain people must be evaluated - for example in asylum procedures.
In such situations, reports by non-native speakers tend to be perceived as less believable even though they may be truthful.
The discovery also explains why people communicating in a foreign language are generally perceived as less trustworthy even though this may not be justified.
"In our globalised world, more and more communication takes place in a language that is not the native language of some or all communication partners," said Kristina Suchotzki from the University of Wurzburg in Germany.
Forensic research has mostly focused on the perceived trustworthiness of people speaking in their native or a non-native language.
this research has revealed that observers seem to be more likely to judge statements of native speakers as truthful compared to statements of non-native speakers.
"Only little research, however, has investigated whether people do indeed lie less well in a non-native language," she said.
The researchers conduced a number of experiments in which up to 50 test persons had to complete specific tasks.
They were asked to answer a number of questions - sometimes truthfully and sometimes deceptively both in their native language and in a foreign language.
While the test participants answered the questions, the scientists measured their response time, skin conductance and heart rate.
They found that it takes longer to answer emotional questions than neutral ones. Answers in the foreign language also take longer than their native language counterparts.
Generally, it takes longer to tell a lie than to tell the truth. However, the time differences between deceptive and truthful answers are less pronounced in a second language than in the native language.
The slight difference does not, however, result from giving a faster deceptive response. Rather in a foreign language, telling the truth takes longer than in one's native tongue, researchers said.
Whether neutral or emotional question, the time differences between telling the truth and lying are generally smaller in a foreign language, researchers said.
"Based on the cognitive load hypothesis, one would have expected increased effort for truth telling and lying in a foreign language, with the increased effort being more pronounced for lying," Suchotzki said.
The data suggest that the increased cognitive effort is responsible for the prolongation of the truth response in the foreign language.
The reason why this prolongation does not exist or is less pronounced in lying can be explained with the emotional distance hypothesis, researchers said.
The greater emotional distance in a foreign language thus "cancels out" the higher cognitive load when lying, they said.