Banner by Sarah Lindley
Can You Really Trust Your Own Memory?
By Navya Reddy
Ask anyone where they were on 9/11 and they will respond with strong conviction and clarity. What about you? When you think about a major event in your life, for example, hearing about school being canceled due to COVID-19, how vivid is the memory? For most people, the memory is detailed and clear. This phenomenon is largely attributed to the concept of emotional memories, memories of events that evoke a strong emotional response. Another term for this is a “flashbulb memory.” In theory, emotional memories are stronger and more vivid, making people recall the details of these experiences with more certainty. However, this concept is contradicted by recent discoveries about eyewitness testimonies.
In the U.S. an estimated 4 to 6% of people currently incarcerated were wrongfully convicted. The Innocence Project, an organization committed to exonerating those who have been wrongfully convicted, has found that for 69% of DNA exonerations, the initial wrongful convictions were driven by inaccurate eyewitness testimony. In these cases, the primary evidence presented against the defendant was eyewitness testimony. But if experiences that elicit strong emotions are supposed to create strong memories, then why are testimonies tied to significant events so inaccurate?
Memory formation consists of three steps: encoding, consolidation, and recall. Encoding is how information is taken in through the five senses, and consolidation determines which information is stored as long term memory. Recall occurs later when the memory is revisited. The second and third steps are primarily associated with the hippocampus, a structure in the temporal lobe of the brain. When emotional memories are encoded, activity in the hippocampus is driven by increased activity in the amygdala. Generally, memories are stronger when the brain is actively paying attention to what it is encoding. In other words, if you deem something worthy of your attention while you are experiencing it, you are more likely to remember it. Intense emotions lead to arousal in the brain, thus an emotional event can lead to more effective encoding. The amygdala, a structure in the temporal lobe, mainly functions to regulate emotion. Within the hippocampal-amygdala region, there are dominant neural connections between both structures. These neural pathways are made through the uncal gyrus. The uncal gyrus is located between the amygdala and hippocampus and consists of the ambient gyrus and the band of giacomini. The strong connections made through this pathway allow for “cross-talk” between the amygdala and hippocampus during consolidation of emotional memories. This increases activity in the region and makes emotional memories unique.
Despite the increase in hippocampal region activity seen during encoding and consolidation, the recall of these memories shows that there are trade-offs. Increased focus on the primary source of the production of strong emotion leads to a decrease in encoding of other details. For example, someone focused on the flames coming out of the window of a house may pay less attention to the person running out the side door. Research has also shown that negative emotions lead to more focal enhancement, while positive emotional memories are more similar to neutral memories in that aspect. Focal enhancement occurs during encoding and consolidation and leads to increased focus on the event itself rather than on the gist of the event. Due to this, people tend to be more confident when recalling negative emotional memories.
A witness’ memory becoming distorted by the interviewer is one route that can lead to inaccurate eyewitness testimony. However, it is less likely that a witness will be susceptible to memory distortion from interviewers’ questions when the memory is tied to negative emotions. In fact, people are likely to be more stubborn or confident in their memory when recalling a negative or shocking event—even if this memory is already inaccurate. This is the main reason why inaccurate eyewitness testimony is so often accepted: the witness is not lying. They wholeheartedly believe that what they are saying is the truth. This makes them seem genuine and believable, leading juries to base convictions on inaccurate information.
Yet testimony can also be inaccurate if the event is given importance after it is encoded and consolidated. For instance, at the time of an event, if a witness does not realize its connection to a crime, but it becomes known to them after it has occurred, their memory may be more likely to be distorted because it was not formed with the strength of an emotional memory.
Additionally, memory can become more distorted with each recollection. This is because with each recollection that memory is reconstructed, making it vulnerable to change. This suggests that every time a witness is asked to recall an event it becomes increasingly malleable, so it is being shaped by the thought processes of police officers and lawyers. For example, if the memory is recalled over and over with the question “was the man wearing a blue jacket and black pants?” as opposed to “what was the man wearing?”, they might slowly shift from only being able to remember that the man was wearing dark clothing to feeling that they remember the exact colors being blue and black.
These factors contributing to inaccuracies in eyewitness testimony largely contradict how people feel about their memories of emotional events in their lives. Ask anyone about the most important or traumatic events in their lives and they will seem to remember them with utmost confidence and certainty. They recall these days with increased vividness, leading them to be confident in their memory. However, the main takeaway of research done on emotional memories shows that increased confidence in memory does not necessarily correlate with increased accuracy. Understanding the dangers in relying solely on eyewitness testimony can help reduce the high number of wrongful convictions in the U.S. and improve our judicial system.