Missing the information needed to perform ROC analysis? Then compute d′, not the diagnosticity ratio

The present experiment tested the applicability of the verifiability approach to the case of an alibi witness. Pairs of truth tellers carried out non-criminal activities. Pairs of liars were separated whereby Member 1 carried out the same non-criminal activities as the pairs of truth tellers while Member 2 committed a mock crime. Participants were asked to provide statements about their whereabouts, whereby pairs of liars were requested to pretend that they carried out Member 1ʹs activities together. Participants were informed that their statements would be assessed in terms of providing verifiable evidence that they had carried out the activities together. Results showed that 88% of the pairs were correctly classified by the verifiability approach. Groups differed in their strategies: Truth-tellers focused mainly on “staying with the truth”, and provided evidence that they were together, whereas liars attempted to make it difficult to refute their claims that they were together.