Viewing an innocent suspect on social media can produce mistaken identifications at a police lineup

What is it about?

Social media poses a problem for police investigations. It allows witnesses to a crime to conduct their own investigations by searching online for images of potential suspects. We highlight this problem by showing that an innocent person is at risk of being mistakenly identified as the perpetrator on social media. Features that are common to social media can make a person stand out in a social media search. We show that an innocent person is at an increased risk of being mistakenly identified on social media when they stand out in a search as having mutual friends. If the person misidentified on social media is then presented in a formal police lineup, the mistaken identification is likely to be repeated. We also found that viewing social media profiles of an innocent person prior to a police lineup affects confidence judgements. When witnesses were highly confident in suspect identifications, prior familiarity with a suspect made these high confidence judgements an unreliable indicator of accuracy.

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Photo by Adem AY on Unsplash

Photo by Adem AY on Unsplash

Why is it important?

Social media makes it easy for witnesses to conduct their own investigations. Numerous cases have involved witnesses using social media to look for a perpetrator, so social media contamination is becoming an issue in cases. Our research shows that identifications made on social media can carry-over to a police lineup. Additionally, we use the mutual friends feature on social media to show that social media features have the potential to be suggestive. Features common to social media can make a person stand out in a search and increase the risk that they will be identified. Finally, our research provides further evidence that contamination of eyewitness memory makes identification confidence unreliable. Suspect identifications made with high confidence can be persuasive in court. Our findings question the reliability of lineup identifications made after a do-it-yourself investigation on social media.