magazine issue 2 2012 / Issue 14

Would you recognize the perpetrator? What do you need to know when you have to make an identification from a lineup?

• written by Melanie Sauerland & Alana C. Krix
• edited by Ishani Banerji

While eyewitnesses cannot be given the power to decide who will be administering the lineup, they will probably be aware of whether or not the lineup administrator knows the identity of the suspect. If this is the case, then the administrator’s behavior may have a substantial impact on the eyewitnesses’ behavior during the identification procedure. For instance, the administrator might indicate agreement with the eyewitnesses’ selection (consciously or unconsciously), which in turn might influence the confidence with which the eyewitnesses express their final decision.

Lineup instructions

When the lineup is presented to the witness, he or she receives an instruction. This instruction should include a warning that the perpetrator may or may not be amongst the persons shown (Steblay, 1997). This measure is to counteract expectancy effects, including the assumption that the real perpetrator is amongst the persons shown, or that the case is almost settled with only the confirming identification evidence of the witness missing. Although the usage of such an instruction can decrease hits, it also decreases false alarms and foil identifications (Brewer & Wells, 2006; Steblay, 1997).

Regardless of how--or whether--the lineup instruction is given, witnesses should always be aware of the fact that it is permissible to reject the lineup, or to say “I don’t know”. Witnesses should always keep in mind that only they have the knowledge about the sequence of events and the perpetrator’s appearance. Therefore, the decision to make a choice (or not) lies exclusively with the witness.

Feedback

When a witness has made his/her identification decision it may seem desirable to receive some sort of feedback regarding this decision. However, positive feedback (e.g., “Good, you identified the suspect”) has an impact on witnesses’ memory for details of the event. For example, participants who have received positive feedback evaluate their memories as clearer, report having had a better view of the perpetrator, and remember having paid more attention to him/her, compared to a no feedback condition (Wells & Bradfield, 1998; Douglass & Steblay, 2002). Furthermore, participants who received positive feedback are more confident about their identification decisions. Negative feedback (“Oh, the suspect was number xy”) has a reversed effect, but less pronounced and not for all of the named variables. Obviously, none of this is conducive to the police investigations.

Witnesses who have received feedback after their identification decisions are advised to display a good degree of suspicion towards their memories of the event. Furthermore, they should take into account that the feedback may have altered their memories. This would also be important to express in court when making a statement about the identification decision.

Cognitive Factors

Lineup presentation

The term lineup presentation refers to the context in which the suspect is shown. While a lineup presents the suspect among several foils, a "showup" only consists of one person. Consequently, a showup instantly reveals the identity of the suspect and offers less protection to innocent suspects. A meta-analysis (Steblay, Dysart, Fulero, & Lindsay, 2003) compared identification performance in lineups vs. showups. Looking at conditions in which the perpetrator was present in the array, the hit rates of these two procedures were about the same. However, eyewitnesses were more likely to accurately state that the perpetrator was not present (thus, resulting in a higher correct rejection rate) in showups than in lineups. Despite this, the showups also produced higher false identification rates when the perpetrator was absent.

Another finding discredits the use of showups. Suspects displayed in showups are mostly arrested, merely because they were close to the crime scenes and generally matched the descriptions provided by the witnesses, including the descriptions of the clothes worn. This can have detrimental consequences in cases in which an apprehended innocent suspect happens to wear the same or similar kind of distinct clothing as the real perpetrator did (Dysart, Lindsay, & Dupuis, 2006).