Eyewitness memory refers to the recollection of events by someone who has directly witnessed them, often serving as critical evidence in legal settings. This type of memory is commonly used in criminal cases where a witness describes details like a suspect's appearance, clothing, or behavior during a crime. However, despite its perceived reliability, eyewitness memory is prone to significant errors.

One such error is memory distortion, which occurs because human memory does not function like a video recording. Instead, memories can fade over time and are vulnerable to reshaping by new or misleading information. For example, if a witness hears a different account of the crime from someone else, their recollection might change to align with the new details, leading to a distorted memory.

Bias is another factor that can affect eyewitness memory, stemming from personal beliefs, societal influences, or media exposure. Bias can shape how a witness recalls and interprets what they have seen. For instance, a witness with preconceived notions about a particular group of people may unconsciously focus on or exaggerate details that confirm these biases while overlooking other aspects of the event. Media coverage can also influence memory; continuous exposure to news stories or crime reports can shape a witness's expectations or beliefs about what they remember, potentially leading to inaccurate testimony.

Emotional stress during the event is another crucial factor that can compromise the accuracy of eyewitness memory. High-stress situations, such as witnessing a violent crime, can impair a witness's ability to perceive and remember details accurately. For example, a person might misremember a suspect's face or actions after a biased lineup or suggestive questioning by investigators. Awareness of these vulnerabilities is essential for legal professionals to critically evaluate the reliability of eyewitness testimonies and develop methods to minimize these errors, such as implementing fair lineup procedures and avoiding leading questions.