I'm preparing for an upcoming oral argument where my main point is that the police irrevocably tainted an eyewitness identification by telling the eyewitness (immediately after she tentatively identified my client from a photographic array) that she had in fact picked the right guy . This police practice actually has a name--positive postidentification feedback. Researchers have conducted studies that show giving positive postidentification feedback (i.e. witnesses are told after picking a suspect out of a lineup or array that they have indeed correctly identified the suspect) can have a profound adverse impact on the reliability of an eyewitness's subsequent identification of a suspect. Articles by the leading researcher into the effects of positive postidentification feedback can be found here. The reason I like this issue so much is that the conduct at issue--a police officer telling an eyewitness that he or she has identified the correct suspect--is completely gratuitous and serves only to reduce the reliability of any subsequent identification. I have posted an excerpt from my appellate brief below that summarizes the research and sets up the argument that an eyewitness who has been tainted by positive postidentification feedback should be precluded from making an identification at trial.
Traditionally, courts have focused on the way a lineup is constructed and conducted to determine if an eyewitness' identification of a suspect is tainted by undue suggestion. For example, it is by now well-settled that a photographic array or live lineup must be conducted in a manner that is fair and not unduly suggestive. (Simmons v US, 390 US 377, 384 ; Wade, 388 US at 228-229; Point I, supra.) However, there is a growing body of empirical research that suggests the police conduct immediately after a pretrial identification can have a profound adverse impact on the reliability of an eyewitness' subsequent identification of a suspect.
Specifically, a 1998 study by researchers at the Iowa State University suggests that "giving feedback to eyewitnesses can result in their recalling that they were more confident in the identification than they really were at the time." (Wells & Bradfield, "Good, You Identified the Suspect": Feedback to Eyewitnesses Distorts Their Reports o the Witnessing Experience, 83 J App Psych 360, 360 .) The researchers described the experiment as follows:
Research participants were shown a grainy security camera video from a Target Store in which a man is shown entering the store. They were told to notice the man as they would be asked questions about him later. After viewing the brief video, they were informed of the fact that the man murdered a security guard moments later. Participants did not see the murder itself on the video. They were then asked to identify the gunman from a photospread. The photospread was the same one used in the actual criminal case, except that we removed the gunman's photo. As shown in prior research, absence of the actual target from a lineup or a photospread leads to a high rate of misidentification, especially when eyewitnesses are not specifically warned that the actual culprit might not be in the lineup. In fact, our procedure was successful in getting every participant to make a false identification. Following the false identification, the experimenter gave confirming feedback ("Good. You identified the actual suspect."), disconfirming feedback ("Actually, the suspect was number ___î), or no feedback. A short time later, the participant-eyewitnesses were asked a number of questions, including how certain they were at the time of their identification decision, how good of a view they got of the gunman's face, how long it took them to identify the gunman from the photospread, and so on.
(Id. at 363.)
The results of the experiment were clear; as explained by the researchers,
This work demonstrates that a casual comment from a lineup administrator following eyewitnesses' identifications can have dramatic effects on their reconstructions of the witnessing and identification experience. A confirming-feedback remark not only inflates eyewitnesses' recollections of how confident they were at the time, it also leads them to report that they had a better view of the culprit, that they could make out details of the face, that they were able to easily and quickly pick him out of a lineup, that his face just "popped out" to them, that their memorial image of the gunman is particularly clear, and that they are more adept at recognizing faces of strangers. These effects were very robust, with effect sizes that exceed what are normally considered large effects in psychology.
(Id. at 374 [emphasis added].)
As the Iowa researchers noted, the practical implications of their findings are profound. "These findings mean that extramemorial factors, having nothing to do with the actual quality of their view or the uncertainty that they actually felt at the time, can distort the eyewitnesses" judgments. This, in turn, means that criteria used to evaluate identification evidence (e.g., the Biggers criteria of certainty, opportunity to view) can actually be driven by the behavior of the agent administering the lineup, in particular the agent's decision regarding whether to give feedback to the eyewitness or not." (Id. at 367.)
This experiment has been repeated numerous times with the same result. (Bradfield, Wells & Olson, The Damaging Effect of Confirming Feedback on the Relation Between Eyewitness Certainty and Identification Accuracy, 87 J App Psych 112 ; Wells, Olson & Charman, Distorted Retrospective Eyewitness Reports as Functions of Feedback and Delay, 9 J Exp Psych 42 ; Semmler, Brewer & Wells, Effects of Postidentification Feedback on Eyewitness Identification and Nonidentification Confidence, 89 J App Psych 334 ; see also, Doyle, Stories of Eyewitness Error, 27 Nov Champ 24 .) Thus it seems clear from the research that positive post-identification feedback essentially destroys whatever reliability an eyewitness's identification may have had, causing even a witness who made a patently false identification believe strongly that the identification was correct, and to exaggerate his or her ability to observe the suspect. "[T]he sensory traces left in memory are, just like blood, drug or semen evidence, subject to contamination. The crucial differences in the memory trace evidence are that if the memory trace is contaminated, there is no uncontaminated sample of the trace left to test, and the contamination may never be proved or disproved by further testing." (Doyle, 27 Nov Champ at 27.)
As caustic an effect as positive post-identification feedback has, it is also a completely unnecessary phenomenon. Unlike some factors that can effect the reliability of an in-court identification, positive post-identification feedback is entirely within the control of the police and thus utterly avoidable:
[p]ostidentification feedback is under the control of the justice system because it is usually given by the person who administers the lineup. That person, usually a detective, knows who the suspect is and, therefore, can give a witness information about the "accuracy" of his or her identification.
(Bradfield, Wells & Olson, The Damaging Effect of Confirming Feedback on the Relation Between Eyewitness Certainty and Identification Accuracy, 87 J App Psych 112, 113 .)
The harmful effect of the type of distortion produced by positive post-identification feedback cannot be overstated. Jurors believe eyewitnesses who are confident in their identification. (Wells, 83 J App Psych at 361 ["There is good empirical evidence to indicate that the confidence with which eyewitnesses give identification testimony is the most important single quality of testimony in terms of whether participant-jurors will believe that the eyewitness correctly identified the actual perpetrator"].) But as the research shows, an eyewitness's confidence has little or nothing to do with the actual accuracy of his or her identification where an investigator immediately confirms the witness's identification of the suspect from a lineup or photographic array. Thus, the police inflate the eyewitness's confidence by confirming an identification, and jurors believe the eyewitness at trial based on that false confidence.