Witnessing an Unfamiliar Person : The Effects of Distance, Lighting, Age, Line-up Type, and Line-up Position on Eyewitness Accuracy

Abstract

In criminal cases, DNA evidence is considered circumstantial evidence, whereas an identification by an eyewitness, after having observed a perpetrator commit a criminal act, is considered direct evidence of a suspect’s guilt. When the police have a suspect in custody and an eyewitness identifies the suspect as the perpetrator of a crime there are, however, many factors that influence eyewitness accuracy. For example, viewing conditions and the age of the eyewitness affect how the eyewitness observes and encodes the perpetrator. Other factors, such as the line-up type used to test the witness, are likely to influence how the eyewitness makes the identification. Importantly, it has been shown that in almost 1900 post-conviction exoneration cases, 70% of the original convictions included misidentifications by eyewitnesses. In the present thesis, we investigated the visual limits of eyewitness accuracy with the aim of finding a threshold where accuracy is so low that identifications should not be used as evidence. We also investigated how the age of the eyewitness and line-up type moderate the visual boundaries of eyewitness accuracy.