Virginia juries usually find eyewitness testimony compelling, but researchers have discovered that our memories can be influenced by our experiences and the questions we are asked. This is because memories evolve in the mind and are shaped by personal beliefs and external factors. Experts call this post-event information. The way post-event information can influence recollections was demonstrated when a researcher asked groups of volunteers to watch a short video of a car accident.
Different vehicle speeds
When a group of respondents who watched the film was asked to judge the speed the cars were traveling at when they struck one another, their guesses were broadly in line with the actual speeds. When another group was asked how fast the cars were moving when they smashed into each other, they guessed the cars were traveling much faster. They also mentioned broken glass and vehicle debris littering the roadway, which was not depicted in the film. The respondents in both groups answered the question they were asked honestly, but the way the question was asked greatly influenced their responses. The question provided post-event information, which shaped their memories.
Researchers have also discovered that personal experiences can impact the way people remember events. They believe the mind fills out incomplete memories with existing information, and police investigative techniques have evolved in recent years to account for this phenomenon. This is why criminal defense attorneys pay close attention to discrepancies in eyewitness accounts and draw attention to them during cross-examinations.
Eyewitness testimony is valued by prosecutors because it is powerful, but it is not always reliable. Memories are malleable things, and they can be shaped by our personal experiences and post-event information. The words police officers use when they question witnesses can influence the answers they receive, and memories may be filled out with existing knowledge.