Fabricated lies are more likely to be mistaken for truth over time

When providing eyewitness testimony, people sometimes fabricate lies that supplement the truth by embellishing or adding new information. This study investigated whether participants confuse their fabricated lies for actually witnessed events over time. In two experiments employing different eyewitness events, participants viewed an event and were then asked to lie about unseen details and events. Memory was assessed after either a 1-week (E1a & E2) or a 4-week (E1b & E2) retention interval. In both experiments, participants falsely reported witnessing their lies after a 4-week retention interval, but only one experiment (E2) obtained evidence for these memory errors at the shorter retention interval of 1-week. In addition, when assessed repeatedly, lies that participants correctly rejected as not witnessed at the 1-week retention interval were later incorrectly endorsed as witnessed when tested again at the 4-week retention interval, thus showing that distinguishing lies from truth became more difficult over time.