From: "R. A. Hettinga" <[EMAIL PROTECTED]> Date: Fri, 25 Oct 2002 08:16:52 -0400 Subject: Eyewitnesses to Crime Often Blinded by Shock, Adrenaline
http://online.wsj.com/article_print/0,,SB1035490650107752191,00.html The Wall Street Journal October 25, 2002 SCIENCE JOURNAL By SHARON BEGLEY Eyewitnesses to Crime Often Blinded by Shock, Adrenaline The hundreds of detectives, police officers and federal agents investigating the D.C. sniper slayings thought they finally had caught a break last week. A couple of people saw a man shoot Linda Franklin, the killer's ninth murder victim, in the parking lot of a Virginia shopping center, a police spokesperson said. But then the fallibility of eyewitnesses reared its ugly head. People who said they saw the shooting offered such conflicting reports that the cops couldn't produce a composite sketch. Only bank records, fingerprints and other forensic data led them to arrest their two suspects Thursday. That comes as no surprise to scientists who study eyewitness memory. As I wrote last month in a column1 on false memories of the 9/11 attacks, even memories of "unforgettable" experiences are a mishmash of first-hand observation confounded by things we heard about, things we saw later, things authorities suggested to us and things we imagined. But in addition to these well-studied influences on memory, which exert their influence after the actual observation, something else is going on: Sometimes we don't see in the first place. It was another murder that showed most poignantly the malleability of eyewitness memory. Gerald Posner, author of the meticulously documented "Case Closed," about the JFK assassination, recalls that during his research for the 1993 book, he encountered "elaborate witness recollections" of "second gunmen, puffs of smoke and mysterious federal agents. In every instance, I went back to the witness's original statements to the police, or to previously unshown television interviews of them that day. The original statements are remarkable for their simplicity and failure to have seen anything of importance." The witnesses saw something that November day. But over time, says Mr. Posner, "Many of them slowly added new elements to their stories, so that after 25 years they had developed elaborate tales that bore absolutely no resemblance to their contemporaneous statements." While some people may have been seeking their 15 minutes of fame, Mr. Posner believes: "Years of reading accounts in books and magazines, watching television and film recreations, talking to other witnesses and the like, filled in gaps in memory. They get to a point where they could pass a lie-detector" test. These are examples of post-event false memory. The National Institute of Justice, the research arm of the Justice Department, now advises investigators to be wary of all the ways eyewitnesses can unintentionally confabulate. But while cops and prosecutors have gotten the word, juries haven't. "For juries, the single most important determinant of a witness's credibility is his confidence, but we know that the most confident witnesses can be the most wrong," says Saul Kassin, professor of psychology at Williams College, Williamstown, Mass. One result: 80% of the 74 convictions later overturned by DNA evidence were obtained through mistaken eyewitness IDs. The leading edge of memory research now focuses on why observations don't make it into synaptic storage in the first place. Thanks to an absence of "encoding," there is nothing in the brain to recall. Why? The list of ways we can fail to encode an observation is fairly dispiriting, but let me summarize two 2001 experiments. In one, two men entered a classroom filled with students -- one "the culprit" and the other "the accomplice." The culprit, a white man, said he had forgotten some slides. He picked up the carousel but dropped it, creating a racket. When the students were later shown a photo lineup, they were pretty good at identifying the culprit when his accomplice was also white. But their accuracy plummeted when his accomplice was black. "The students had a tendency to keep their eye on the black man," says psychologist Stephen Goldinger of Arizona State University in Tempe, who led the study. "A distinctive person receives more attention than a 'typical' person. This suggests that white culprits may be forgotten, or mistaken for other white bystanders, if a black person is even present." In another study, neuroscientists in London used brain imaging to investigate cortical activity when people detect, or fail to detect, a change in a scene. They found that unless the brain's attention area is activated, people literally don't see the change. Photons striking the retina aren't enough. Adrenaline can also blind you. "A little arousal is good for memory, but the effect looks like an inverted U: when adrenaline first increases, memory improves, but as it keeps going up performance goes down," says Prof. Goldinger. Memory also can be impaired by the presence of a weapon -- or any attention-getting object. If you see a robber handing a teller a celery stick, memory for the robber's appearance stinks. Which returns us to the sniper. "When you have a very upsetting event like a woman being shot, what suffers is your memory for peripheral detail," says Elizabeth Loftus, professor of psychology at the University of California, Irvine. Investigators, it seems, will have to build their case on forensics.
