New study shows eyewitness memories of police lineups are often incomplete

A new study from Florida International University reveals that witnesses remember feedback about their performance more accurately than the instructions they received before a police lineup. This asymmetry in recall creates a specific vulnerability in the justice system, where the details of the identification process can fade or shift over time.

Stephen Charman, a professor in FIU’s Department of Psychology, led the research into how accurately witnesses remember the identification process. His work addresses a long-standing concern: whether the legal system can rely on eyewitnesses to correctly identify a suspect. The findings suggest the answer is mixed. While witnesses can be truthful, their memory of the procedure itself is not always reliable.

The study identifies that witnesses often forget what officers said before the lineup or what occurred immediately after. When these gaps appear, witnesses may unconsciously fill them in with what they think probably happened. This is not an attempt to mislead; rather, it is an effort to make sense of an experience that is no longer clearly remembered. As Charman noted, “When misinformation gets incorporated into your memory, it becomes almost indistinguishable from it.”

Leading questions can further alter these reports, especially when the original memory is weak. Witnesses may be questioned long after the initial identification, during later stages of a criminal case. By that point, the specifics of the procedure may have blurred. Charman explained that people are often unaware of how their memories have been influenced in the past, stating that it “feels real to them.”

The practical implication for the courtroom is a reliance on memory rather than objective records. Without video recordings of the identification, legal proceedings depend on the witness’s recollection of the procedure. Defense attorneys are particularly concerned with whether the line of procedure was executed correctly. “Defense attorneys want to know if the line of procedure was done correctly, because if it wasn’t, that might be an explanation for why their client was identified,” Charman said.

The error can work in both directions. A witness might recall a procedural error that did not exist, casting doubt on a valid identification. Conversely, a genuine mistake might be forgotten, allowing a flawed process to stand unchallenged. In either scenario, judges and juries evaluate a version of events that may differ from reality. The research points to video recording as a method to create a permanent record, preserving the facts before memory alters them.

The study does not suggest that eyewitnesses should be dismissed. Instead, it outlines the mechanical limits of human memory. By documenting the procedure, the legal system can separate the witness’s account of the crime from their account of the police process, reducing the risk that inference replaces observation.