Countering information leakage in the Concealed Information Test: The effects of item detailedness

Concealed Information Tests (CIT) are administered to verify whether suspects recognize certain features from a crime. Whenever it is presumed that innocent suspects were contaminated with critical information (e.g., the perpetrator had a knife), the examiner may ask more detailed questions (e.g., specific types of knives) to prevent false positives. However, this may increase the number of false negatives if the true perpetrator fails to discern specific details from its plausible irrelevant controls, or because detailed crime‐scene information may be forgotten. We examined whether presenting items at the exemplar level protects against contamination, and whether it compromises the sensitivity in a physiological CIT. Participants (N = 142) planned a mock‐robbery, with critical items encoded either at the category or at the exemplar level. The CIT was administered immediately or after a 1‐week‐delay, with questions phrased at the categorical or exemplar level. There were no effects of time delay. Results revealed that when item detailedness was congruent at encoding and testing, the SCR, HR, and RLL showed larger differential responses, as compared with incongruent conditions. Participants contaminated with crime knowledge at the categorical level did not show a CIT‐effect for crime details at the exemplar level, suggesting detailed questions may counter the leakage problem. Asking questions at the exemplar level did not reduce the CIT detection efficiency as compared to asking questions at the categorical level. The importance of congruency between encoding and testing provides examiners with a challenge, as it is difficult to estimate how details are naturally encoded

Extending the scope of concealed information detection

Determining the true perpetrator of a crime while exonerating innocent suspects forms the foundation of a fair justice system. Specific psychophysiological and behavioral responses, indicating knowledge of critical details derived from a criminal investigation, have been found effective in linking individuals to a crime. While the theory underlying memory detection and the mechanisms contributing to these response patterns have been investigated thoroughly, important questions regarding the external validity remain unanswered. The current dissertation extends the body of knowledge on concealed information detection in three ways. First, research participants have typically been instructed to commit staged crimes, whereas actual perpetrators freely choose whether or not to engage in antisocial behavior. The findings suggest that intrinsic, self-initiated behavior does not undermine CIT validity. Second, memory detection techniques can accurately detect the presence of a memory, but not its origin. Results indicate that presenting items at the exemplar level may reduce the risk of false positives otherwise expected when innocents are contaminated with crime information. Moreover, the appropriate level of questioning in memory detection (using categorical or exemplar details) depends on the initial memory formation at the crime scene, thereby challenging examiners to adopt a perpetrators’ perspective when selecting items. Third, the field lacks an independent method to assess the veracity of suspect confessions. A new application of memory detection shows that recognition of critical details could distinguish true from false confessors. Taken together, the present dissertation provides insight into the external validity of memory detection to enhance the application in the legal arena