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

It is straightforward that witnesses’ identification decisions depend on cognitive factors, such as the memory strength regarding the perpetrator. A less intuitive cognitive factor may be the context in which the suspect is put in the recognition situation; that is, the manner in which the lineup is presented. Furthermore, social and meta-cognitive influences also play an important role (Brewer, Weber, & Semmler, 2007). Social influences include expectancy effects identified through Robert Rosenthal’s (1966, 2002) research on the effect of teachers' expectations on schools students. Meta-cognitive variables concern our intuitive theories of how memory works (e.g., “If I’m highly confident, I should be correct”; Winkielman & Schwarz, 2001). In the next section we discuss social, cognitive and meta-cognitive variables that can influence witnesses’ decision making during the identification procedure.

Social Influences

Lineup administration--double-blind testing

While a lineup is presented, neither the witness nor the lineup administrator should be aware of the suspect's identity--a technique known as double-blind. This helps to guard against the experimenter effect (Rosenthal, 1966, 2002), a well-known phenomenon in social psychology in which the experimenter's expectations drive participants' behaviors. Transferred to eyewitness identification, the experimenter effect can cause the lineup administrator to give the witness – consciously or unconsciously - verbal and nonverbal cues about the identity of the suspect (Quinlivan, Neuschatz, Cutler, Wells, McClung, & Harker, in press). This can lead to an increase in false alarms (Phillips, McAuliff, & Cutler, 1999) without witnesses being aware of the impact the administrator has on their decisions (Greathouse & Kovera, 2008).

However, a police officer blind to the identity of the suspect cannot exert such influence. For real-world cases, this means that the investigating police officer must not administer the lineup.

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.