Investigating Investigators: Examining Witnesses' Influence on Investigators.

Abstract

This research examined the influence of eyewitness identification decisions on participants in the role of police investigators. Undergraduate "investigators" interviewed confederate "witnesses" and then searched a computer database of potential suspects. The database included information on each suspect's physical description, prior criminal record, alibi, and fingerprints. Participants selected a suspect and estimated the probability that the suspect was guilty. Investigators subsequently administered a photo lineup to the witness and re-estimated the suspect's guilt. If the witness identified the suspect probability estimates increased dramatically. If the witness identified an innocent lineup member or rejected the lineup, investigators' probability estimates dropped significantly, even when pre-lineup objective evidence (e.g., fingerprints) was strong. Performance of participants acting as witnesses in two baseline studies was at chance. Therefore, participant-investigators greatly overestimated the amount of information gain provided by eyewitness identifications.

Post‐identification feedback effects: Investigators and evaluators

“…The current research provides additional evidence of bias driven by investigative tunnel vision (Findley & Scott, 2006;Meissner & Kassin, 2004) and contributes to the groundswell of literature exploring witness evidence and investigator decision making (e.g. Boyce et al, 2008;Dahl et al, 2006Dahl et al, , 2009Lindsay, Nilsen, & Read, 2000). We raise the caution that the magnitude of investigator influence observed in our research may be greater in the real world where police officers bring the power of their authoritative position to the context of the investigative interview.…”

“…Whereas eyewitnesses and jurors have been the focus of studies by psycholegal researchers for more than 30 years, empirical studies focused on police investigators have emerged only in the last few years. This recent research reveals that participant-investigators are greatly influenced by witnesses' line-up decisions (Boyce, Lindsay, & Brimacombe, 2008;Dahl, Lindsay, & Brimacombe, 2006). An investigator's belief in the suspect's guilt grows stronger when an eyewitness identifies the suspect and declines when the witness chooses a foil or rejects the line-up.…”

The Emotional Child Witness: Effects on Juror Decision‐making

“…Allowing jurors to deliberate could provide novel insight into the salience of the child's emotional displays and jurors' perceptions of the child's emotionality during the decision-making process. Jurors may also become aware of their own relevant biases (e.g., what emotions are appropriate to a truthful witness) through deliberation discussions, altering their evaluations of the child's credibility and the case (Dahl, Lindsay & Brimacombe, 2006).…”

Witness Vetting: What Determines Detectives' Perceptions of Witness Credibility?

“…Current evidence suggests that investigations can be influenced by affective elements of a case, time pressure, and context that can foster detective confirmation bias (Ask, Rebelius, & Granhag, ; Ask & Granhag, , ; Bollingmo, Wessel, Eilersten, & Magnussen, ; O'Brien, ). Investigators have preconceived ideas about the amount and type of evidence that is important to a given case (Dahl, Lindsay, & Brimacombe, ), and the order in which detectives receive witness and alibi information influences detectives' decisions (Dahl, Brimacombe, & Lindsay, ), but it is unclear how these factors influence witness vetting.…”