Recently, it became common to hear people belittle the discipline of history. To understand a past event, some say, you must have been there. It is said that the opinions of people who weren’t alive at the time are null.
At first glance, this sounds like a tempting notion. We humans, after all, have firm confidence in the accuracy of memories, which is why we put a premium on the stories told by firsthand witnesses. Reading about something in the news or from an academic source just doesn’t feel as convincing as hearing it from someone who was really there in the thick of it, especially if that someone is a person you know and trust.
The science, however, is clear: eyewitness reports, on their own, are never as reliable as hard data.
Before we return to that point, let us first look at how absurd the claim that only those who witnessed a past event can understand it. If we only relied on firsthand reports, both science and history would not be possible in the first place.
Think for a moment about the fact that no one alive today was there to witness most of history. Worse, no one alive today was there to witness the evolution of humankind, the rise and fall of the dinosaurs, or the formation of the Solar System.
Both science and history are possible only because we can connect the evidence and indirect observations in a logical way to form consistent and testable stories. We understand past events not because we have lived through them, but because science allows us to act like good detectives. Like good detectives, we arrived at the scene some time after the event. There, we collect the evidence and piece them together to form a scenario that best fits the evidence.
Treating science and history as detective stories rather than as firsthand narratives becomes even more important in cases when there are eyewitness reports available. Firsthand accounts can be very convincing. However, their accuracy is very limited.
Ever since the 1990s when DNA testing was first introduced, an organization called the Innocence Project has been collecting data on court convictions and DNA evidence. The results of their research are devastating. Just to give one example, they found that out of 239 court convictions that were overturned by DNA evidence, 73 percent were based on eyewitness testimony. In other words, nearly three quarters of those first found guilty and later found innocent were pronounced guilty because of the testimony of witnesses.
Research has shown that the testimony of eyewitnesses, especially confident ones, can have a very strong influence on the decision of jurors. However, given the data from the Innocence Project, that is worrying. What makes it even more worrying is that other researches have shown that the confidence of an eyewitness is not a predictor of the accuracy of their testimony.
Because of these findings, there are many moves today to educated jurors of the limitation of eyewitness reports and the importance of other sources of evidence such as the forensic sciences.
There are many reasons why careful investigation, even by people who have never witnessed an event firsthand, can be more reliable than eyewitness reports.
First, the human senses and their recording into memory are flawed. Second, recalling a past event is also a deeply flawed process.
Many of us imagine recalling a past event as something comparable to playing a recorded video. We now know that this is wrong. When we try to remember things, our mind actually reconstructs our memory.
Decades of research by psychologists have found many biases and flaws in this process of reconstruction. For example, we tend to recall only facts that agree with our beliefs and forget those that don’t. We also tend to remember events that put us in a good light and forget events that put us in a bad light. The emotions we felt at the time of an event also affect how we remember it.
Even more damning, research has shown that people can be easily given false memories. In one well-known study researchers asked respondents to recall the details of four events, three of which were true and one was fictional. Close to one-third of the respondents reported remembering the false event. In a follow-up study, 25 percent still reported remembering the untrue story.
Equally damning, other studies have shown that the way we are asked about a past event affects how we remember it, how our brains reconstruct our memories of that event.
All this should make us take a somber view of the accuracy of eyewitness reports and make us appreciate the power of the methods of science and historical analysis. Our grandparents’ stories have value, but they alone do not constitute history.
Decierdo is resident astronomer and physicist for The Mind Museum.
