Testing a ''Not Sure'' Instruction as a Prophylactic Against the Harmful Impact of System and Estimator Variables on Lineup Identification Accuracy, United States and United Kingdom, 2019-2023 (ICPSR 38947)
Eyewitness lineup identification accuracy is affected by numerous variables, including those that are under the control of the legal system, called system variables (e.g., pre-lineup instructions), and those that are not under the control of the legal system, called estimator variables (e.g., the race of the perpetrator). One of the ultimate goals of eyewitness researchers is to develop procedures that:
- minimize false identifications caused by system and estimator variables (while minimizing any decrease in correct identifications), and
- require few resources for law enforcement to enact.
The project tested the effectiveness of a system variable--providing witnesses with an explicit 'not sure' instruction before viewing the lineup-- that potentially meets both of these criteria. Furthermore, a 'not sure' instruction may act as a prophylactic against the harmful effects of system and estimator variables known to inflate false identifications. The specific objective of the research was to test the effectiveness of this 'not sure' instruction.