Deceiving suspects about the content of their alibis: Consequences for truthful and untruthful suspects

Purpose - The purpose of this paper is to test how modifying one's alibi statement interacts with exposure to deceptive interrogation techniques.

Design/methodology/approach - In all, 90 participants walked about a university building for 15 minutes and either stole an envelope from a staff pigeonhole (guilty condition) or put the envelope there along the way (innocent condition). Subsequently, participants were asked to provide an alibi for the past 15 minutes. Guilty and half of the innocent participants were instructed to omit that they had been in the vicinity of the pigeonholes. The rest of the innocent participants were asked to tell the truth. Several days later, participants were questioned about six statements taken from their alibis, three of which contained altered information.

Findings - As expected, participants were largely blind to our alterations, with detection rates ranging from 1 to 36 percent. Contrary to cognitive load predictions, detection rates did not vary as a function of truthfulness. Rather, guilty participants were less likely to detect alterations than innocents.

Research limitations/implications - Memory distrust and guilty suspects' aim to keep a low profile might be possible explanations for these findings.

Practical implications - It is recommended that law enforcement officers and other legal practitioners refrain from using deceptive interrogation techniques and such techniques that can cause inconsistencies in suspects' reports. Researcher should make it their task to educate these professional groups about the natural occurrence of memory related, non-deceptive inconsistencies in successive statements.

Originality/value - This research uses a new methodology to study the effect of deceptive interrogation techniques on both innocent and guilty suspects. The findings are relevant for legal practitioners and researchers.