Human memory is a complex phenomenon. It does not act like a tape recorder, laying out events exactly as they occurred, but rather is a series of impressions guided by emotions, expectations and biases. Moreover, research dating as far back as the 1930s has shown that memories can change over time in response to stimuli such as reconsideration, repetition and outside influence.
This is important to understand when assessing eyewitness testimony and suspect identifications. A seminal paper published in 1978 concluded that many common techniques police use in lineups and photo arrays can unduly influence eyewitnesses.
How the subjects are presented, the instructions given to the witnesses, and even police body language can lead witnesses to choose a particular person suspected by the police. Far too often, this results in a false identification.
Mistaken identification is a serious problem in the U.S. According to the Innocence Project, misidentification played a role in 71 percent of some 350 wrongful convictions overturned by post-conviction DNA evidence. The National Registry of Exonerations estimates that misidentification was a factor in at least 29 percent of 2,245 exonerations since 1989. The difference in percentages may be due to the fact that the Innocence Project tends to focus on sex offenses and homicide.
Nevertheless, law enforcement agencies across the U.S. have continued to rely on leading techniques. However, that may be changing.
It may be the emergence of DNA-based exonerations that highlighted the need for change, according to the Pew Charitable Trusts’ Stateline. DNA can provide high-quality proof that a given defendant could not have perpetrated the crime. That requires police and prosecutors to reassess evidence in which they were confident, such as identifications made by eyewitnesses.
As a result, many police departments have begun reforming their procedures for lineups and photo arrays to be less suggestive of a particular result. Implementing reforms is a big job — most policing is done by individual, local departments with little to no coordination. However, police departments in about half of states, including Wisconsin, have taken on the challenge.
What practices would improve the reliability of eyewitness IDs?
Evidence-based recommendations have been made by groups including the National Academy of Sciences and the International Association of Chiefs of Police, and law enforcement is increasingly setting policies that reflect them. The recommendations include:
- Setting up the lineup or photo array using one suspect and at least five non-suspects who match the witness’s general description of the perpetrator.
- Making lineups and photo arrays openly “double blind.” This means that the officers involved are not told which person is the suspect, and the witness is made aware of that fact. When witnesses are aware that the officer is unable to help, thy are less likely to seek cues from the officer.
- Telling witnesses that the perpetrator might or might not be in the lineup or array. That way, the witness will not simply choose the person closest to their memory under the assumption that the police have arrested the correct suspect.
- Having the witness indicate their level of confidence in their identification.
- Videotaping the identification process from start to finish so that it can be reviewed later.
False identifications lead to far too many wrongful convictions. Unfortunately, that typically means the actual perpetrator has gone free and the trail has gone cold.