Witnesses' verbal evaluation of certainty and uncertainty during investigative interviews: relationship with report accuracy

The Enhanced Cognitive Interview (CI) is a widely studied method to gather informative and accurate testimonies. Nevertheless, witnesses still commit errors and it can be very valuable to determine which statements are more likely to be accurate or inaccurate. This study examined whether qualitative confidence judgments could be used to evaluate report accuracy in a time-saving manner. Forty-four participants watched a mock robbery video and were interviewed 48 h later with a revised CI. Participants' recall was categorized as follows: (1) evaluated with very high confidence (certainties), (2) recalled with low-confidence utterances (uncertainties), or (3) recalled with no confidence markers (regular recall). Certainties were more accurate than uncertainties and regular recall. Uncertainties were less accurate than regular recall; thus, its exclusion raised participants' report accuracy. Witnesses were capable of qualitatively distinguishing between highly reliable information, fairly reliable information, and less reliable information in a time-saving way. Such a distinction can be important for investigative professionals who do not know what happened during the crime and may want to estimate which information is more likely to be correct.
The Portuguese Foundation for Science and Technology supported this work under the grant number SFRH/BD/84817/2012, attributed to the main author, Rui Paulo.This study was conducted at the Psychology Research Centre (UID/PSI/01662/2013) at the University of Minho, which is also supported by the Portuguese Foundation for Science and Technology and the Portuguese Ministry of Science, Technology and Higher Education through national funds and co-financed by FEDER through COMPETE2020 under the PT2020 Partnership Agreement (POCI-01-0145-FEDER-007653).