Using a model statement to enhance the verifiability approach

The present experiment investigated to what extent providing participants with a model statement influences the ability of the verifiability approach to detect deception. Participants gave a true and false statement about a negative autobiographical event, with half of the participants receiving a detailed model statement just before giving their statement. We expected false statements to include more non-verifiable and less verifiable details than true statements, and that providing a model statement would increase these differences. False statements indeed included more non-verifiable details than truthful statements but did not differ in number of verifiable details. True statements included a higher ratio of verifiable details. The model statement encouraged participants to give a longer and more detailed statement. However, it prompted participants to increase the number of included verifiable – and not non-verifiable – details, regardless of veracity. Using a model statement did not influence the discriminability of the verifiability approach.