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Newly released court documents in the second-degree-murder case against neighborhood watch volunteer George Zimmerman reveal that, in the month following his fatal shooting of Trayvon Martin on Feb. 26, four key witnesses significantly changed their accounts of what they saw and heard that night. The more recent versions of their memories tend to be more damning of Zimmerman than their initial statements.
Which raises the question: How reliable are eyewitnesses?
For example, days after the shooting, one woman told police she had seen two men running through the streets and then engaging in a fistfight. Less than one month later, she told investigators she saw just one person running, and couldn't describe his or her appearance as she hadn't had her contact lenses in at the time.
Another witness, who was initially interviewed March 20, said she saw two people on the ground immediately after the shooting but was not sure which one was on top. In another interview with investigators six days later, she said it had definitely been Zimmerman on top, explaining that she was sure because she had been able to compare Zimmerman's and Martin's sizes after seeing them on TV.
A third witness originally said he saw a black man (presumably Martin) pinning down and punching a lighter-skinned man (Zimmerman) who was calling for help. Later, the witness wasn't sure any punches were thrown or that he had heard distress calls.
And a man who initially described Zimmerman as looking bloody and in shock after the shooting later implied the shooter had been calm, cool and collected.
Why do people's memories change over time? And which versions of these witnesses' stories are to be believed — the earlier ones untarnished by time, or the later ones, perhaps less sullied by what may have been false impressions imbued early on by news reports or police interviewers?
The reliability of witness testimony is a vastly complex subject, but legal scholars and forensic psychologists say it's possible to extract the truth from contradictory accounts and evolving memories. According to Barbara Tversky, professor emerita of psychology at Stanford University, the bottom line is this: "All other things equal, earlier recountings are more likely to be accurate than later ones. The longer the delay, the more likely that subsequent information will get confused with the target memory."
However, in some cases not all other things are equal.
How we remember
Memory is a reconstructive process, says Richard Wise, a forensic psychologist at the University of North Dakota. "When an eyewitness recalls a crime, he or she must reconstruct his or her memory of the crime." This, he says, is an unconscious process. To reconstruct a memory, the eyewitness draws upon several sources of information, only one being his or her actual recollection.
"To fill in gaps in memory, the eyewitness relies upon his or her expectation, attitudes, prejudices, bias, and prior knowledge. Furthermore, information supplied to an eyewitness after a crime (i.e., post-event information) by the police, prosecutor, other eyewitnesses, media, etc., can alter an eyewitness's memory of the crime," Wise said in an email. [How Are Memories Stored in the Brain?]
That external input is what makes eyewitness testimony so unreliable. Eyewitnesses are generally unaware that their memory has been altered by post-event information, and feel convinced they're recalling only the incident itself. "Once an eyewitness's memory of the crime has been altered by post-event information, it is difficult or impossible to restore the eyewitness's original memory of the crime," Wise told Life's Little Mysteries.
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9 Comments
Add Comment"Which raises the question: How reliable are eyewitnesses?"
Reply | Report Abuse | Link to thisWhy would this, rather than any other case, raise this question? It's old, it's answered, and it's not news.
Ask any cop - no, they're not.
Studies have shown that the more details involved the less reliable the eyewitnesses account of the scene and vice versa. Humans will also use available information to make decisions. Car salesman know this. They only tell you what will help you make the decision to buy the car. Good attorneys know this too. Defense attorneys will ask questions that indirectly provide details so an eyewitnesses testimony will be inconsistent and thus less reliable.
Reply | Report Abuse | Link to thisDid you see the Rodney King beating video. Indisputable evidence of law enforcement using unnecessary force, yet an attorney was able to convince jurors they didn't see what they watched happen on the video.
It's all so known that the victims them selves can get it wrong. Yet the victims testimony is considered important in convicting the accused.
Reply | Report Abuse | Link to thisNote that at least one of the cases of "eyewitness recanting" actually is not!
Reply | Report Abuse | Link to thisThe second witness said she couldn't tell who was on top, but, then, after seeing the two men, whose sizes were significantly different, she knew who was on top.
That doesn't mean here memory has changed!
That means that she still rememebers if it was the heavier set person on top on or not and that, now, after she knows Zimmercan was the chunkier individual, she knows it was hm!
This is an artificial "argument" intended to attack the credibility of wyewitnewsses!
And, because it is partently illegitimate, yet being passed off as such in a supposedly reputable "science" magazine to give ti "legitimacy" it doesn't deserve, that is proof eyewitness testimony is valid and there is a conspiracy among those in power to eliminate reliance on it!
The first portion of this article seems to be exactly the same as I have seen in other articles discussing the witness testimony. If you cut and paste shouldn't you have an attribution for the material?
Reply | Report Abuse | Link to thisI noticed partially because of the same error in the same words, "Later, the witness wasn't sure any punches were thrown or that he had heard distress calls." This witness actually said it was too dark to see whose mouth was open to match to the screams, not that there were no screams.
Memory isn't the only factor here, the witnesses are responding to questions in this latest round from prosecution investigators. Without knowing what those questions were, how they were framed, it is a mistake to put much weight in the literal reply, which could mean other than in does in context with the specific question and related questions.
I once had to subdue a violent fellow by conking him out with a flashlight. The police charged him with a few offenses and he was released on bail. His time in front of a judge came up a few weeks later. I was relieved when he didn't show because I had been asked to appear and identify him. I couldn't remember what he looked like.
Reply | Report Abuse | Link to thisYes, too weird. I'm usually good with faces but in the heat of the moment and ever the aftermath, my brain was in some other mode.
Been there myself. Had to ID a person on a moped who knocked a kid over. It took a good minute before I was sure I was looking at the same guy.
Reply | Report Abuse | Link to thisPlease sign and share this petition to have Casey Anthony tried by the federal government.
Reply | Report Abuse | Link to thisDouble jeopardy is subject to what is known as the "dual sovereignty" doctrine. This doctrine states that a person can be tried for the same crime twice, if he is being tried by more than one distinct, sovereign government. This means that a person can be tried by the federal government and by a state government for the same crime. Both entities are distinctly sovereign units that have their own sets of laws and their power derived from different sets of people.
The petition address the DOJ policy that guides them in deciding whether or not to bring federal charges against someone after a person has already been tried by a state.
http://www.change.org/petitions/lanny-a-breuer-assistant-attorney-general-criminal-division-try-casey-anthony-in-federal-court-for-the-murder-of-her-daughter
Aside from eyewitnesses being generally unreliable, in this particular case anyone who offered testimony that may be favorable to Zimmerman would be under overwhelming social pressure to retract or revise it. Because this case has been framed by the media as being racially motivated, anyone who helps the white guy is going to be suspected of being a racist, even if they're black.
Reply | Report Abuse | Link to thisThis is what happens to justice when the racial hucksters get involved. The crime is no longer judged on the basis of the objective evidence, but on its racial implications. The perception is that if Zimmerman is acquitted, it will be bad for blacks (and may start civil disturbances), and if he is convicted it will be a great day for civil rights.
This is not the way the criminal justice system should be and it would not be happening in a race-neutral and color-blind society, which is not what racial hucksters want.