A recurring element found in many known cases of wrongful conviction is eyewitness misidentification. Eyewitness testimony is especially powerful in convincing a jury of guilt - oftentimes, the witness' veracity and emotionality is taken at face value, without the requisite degree of skepticism.  Unfortunately, eyewitness testimony has been proven to be highly unreliable.

Problems with witness' identification occur at many points throughout the recollection process, and are variable depending on the particular circumstances.  The impact that a particular event may have influences memory from the original perception, through the memory storage and recall stages.

Being present during the commission of a crime - especially one involving weapons - is a stressful experience. Psychological research has shown that in high-stress situations, our attention focuses on particular elements that we perceive as posing the greatest risk (i.e. the weapon).. This focus diverts our attention from other details of the scene - such as the identifying characteristics of the perpetrator.

It has also been shown through scientific testing that our minds fill in the gaps in our perception and memory after an event has ended. Even though a witness may not have clearly perceived the features of the perpetrator, the mind fills in the blanks with information it gathers later. For example, if a witness later sees a picture of the accused on television or in the newspaper, the witness may use those details to erroneously fill in details that were missed during the actual encounter. Once that erroneous information is stored in memory, the witness will not be able to distinguish their actual perceptions from those constructed after the fact. Furthermore, as time passes and the witness continues to think about the (erroneous) details, the witness can become even more confident in their misidentification.

The accuracy of eyewitness identification is also influenced by the way investigators interview potential witnesses. Either intentionally or subconsciously, an investigator conducting a lineup may give a witness subtle cues regarding who the "right" suspect is - the suspect that the police believe is the perpetrator. There are several ways in which this happens. In conducting photographic lineups with witnesses, the police often use a "simultaneous" lineup - in other words, they show the witness the photographs of several people who are potentially the perpetrator. Scientific research shows that when a simultaneous lineup is used, a witness will choose the individual who most closely resembles their memory of the perpetrator - regardless of whether the perpetrator is even actually present in the lineup. With a suspect now chosen, the mind fills in the gaps which were missing from memory, and the witness becomes certain that the picture they have chosen is in fact who they saw.

Often, before interviewing witness, police will already have a suspect in mind which they believe is guilty. This sometimes leads to subtle (or explicit) cues to the witness on which individual to identify. For example, if a witness identifies a suspect that does not match the police's theory, the police may ask them to check again to be certain - and the police can continue this process until the witness selects the individual who matches the police theory.

A witness' identification of a suspect can also be influenced by the characteristics of the lineup itself. If a lineup contains potential suspects that vary greatly in their characteristics, the witness is likely to choose the suspect that most closely matches the vague memory they have of the perpetrator's characteristics. An extreme example of this phenomenon would be if the known perpetrator had a beard, but only one of the members of the lineup had a beard.

Given the strong weight given to eyewitness identifications by juries, and their proven inaccuracy as a fact-finding tool, it is not surprising that faulty eyewitness identifications are implicated in many known cases of wrongful conviction.

[prepared by Moheb Tewfik, class of 2008]

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