It’s a match!? Appropriate item selection in the Concealed Information Test

BACKGROUND: While the Concealed Information Test (CIT) can determine whether examinees recognize critical details, it does not clarify the origin of the memory. Hence, when unknowledgeable suspects are contaminated with crime information through media channels or investigative interviews, the validity of the CIT can be compromised (i.e. false-positive outcomes). Yet, when the information was disclosed solely at the category level (e.g. the perpetrator escaped in a car), presenting specific items at the exemplar level (e.g. Citroën, Opel, or Volkswagen) might preclude this problem. However, diminished recollection for exemplar-level details could attenuate the CIT effect for knowledgeable suspects, thereby leading to false negatives. The appropriate item level for memory detection to reach an optimal balance between sensitivity and specificity remains elusive. As encoding, retention, and retrieval of information may influence memory performance and thereby memory detection, the current study investigated the validity of the CIT on both categorical and exemplar levels. RESULTS: Participants planned a mock robbery (n = 165), with information encoded at the category (e.g. car) or exemplar (e.g. Citroën) level. They were tested immediately or after a one-week-delay, with a response time-based CIT consisting of questions at the categorical or exemplar level. An interaction was found between encoding and testing, such that CIT validity based on reaction time was higher for “matching” (e.g. exemplar-exemplar) than for “mismatching” (e.g. exemplar-categorical) items, while immediate versus one week delayed testing did not affect the outcome. CONCLUSION: Critically, this indicates that what constitutes a good CIT item depends on the way the information was encoded. This provides a challenge for CIT examiners when selecting appropriate items. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s41235-019-0161-8) contains supplementary material, which is available to authorized users.