The challenge of speaking in a foreign language is similar to the stress felt by people who are telling a lie.

Both groups change their physical behaviour as a result, which may cause a second language speaker to act in a way associated with lying.

This was the finding of a recent study by PhD candidate Sophie Van Der Zee and Professor Paul Taylor from Security Lancaster at Lancaster University.

The paper “Nonverbal mimicry increases in second language interviews” won best student paper prize at the recent European Association of Psychology and Law conference.

Sophie Van Der Zee summarised: “Police forces in the United States and Europe are reporting significant growth in the cultural diversity of interviewees and the range of language skills encountered in the interview room. When examining a suspect’s behaviour for cues that reveal deceit, a distorted image can arise when the suspect is speaking in their second language because both cognitive load and anxiety can cause behavioural changes that match those used to predict deceit.”

Fifty six people took part in the study in which they wore full body motion capture suits to record their position 120 times a second to capture the extent of their behavioural mimicry.

The participants were asked either to lie or tell the truth about their memories of several tasks, either in their first language, Dutch, or in their second language, English.

Previous research by the authors had shown that first language interviewees increase their mimicry of the interviewer when lying. These results confirmed the previous finding but also suggest that other factors, such as second language use, may play a critical factor in how a person appears during interview. This, in turn, may impact on interviewers’ perceptions of their guilt.

Security Lancaster brings together Lancaster University’s research in cyber security, security futures, violence and society, transport and infrastructure security, and investigative expertise.