We Are Naturally Bad Sleuths.. and Frequently Fail to Find the Truth

How could 10 witnesses have all said they were certain a defendant was the perpetrator of the crime, when DNA testing later proved that he was innocent?
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Memory lapses are not as simple as occasionally forgetting where we left our keys. Elizabeth Loftus's talk, "The Fiction of Memory," shows how human memory is far weaker and more malleable than most of us realize. Unlike a tape recorder, which plays back verbatim, our memories are like quick-sand, forever moving and shifting underneath us, creating distorted or entirely false memories in the process. And we are surprisingly susceptible to having our memories permanently altered by even the slightest suggestions from others. The scariest part of it is that we are not aware of how much our memories are in flux, and by nature believe our distorted memories to be 100 percent accurate.

Although differing memories can contribute to such things as family squabbles about who was last seen holding the missing TV remote, Loftus shows how the frailties of human memory affect the criminal justice system, and can cause the wrongful conviction of innocents. This happens, for example, when witnesses remember what they saw incorrectly, and identify an innocent person as the perpetrator. Mistaken eyewitness identification has proven to be the leading cause of wrongful conviction, playing a role in 75 percent of the cases. In many cases where a defendant was later proven innocent, multiple witnesses -- in one case as many as 10 witnesses -- testified with certainty that the man on trial was the person they saw commit the crime.

Loftus's research on memory is partially an outgrowth of the Innocence Movement -- the phenomenon of suspects being convicted and sent to prison for inhumane crimes they didn't commit, only to find out years later, usually through DNA testing, that they were 100 percent innocent. The National Registry of Exonerations now lists more than 1,200 wrongful convictions of innocent people since 1989, some of whom were represented by my organization -- the Ohio Innocence Project. And while our society has grown accustomed to turning on the news and seeing an innocent man or woman walking out of prison after serving 20 or 30 years for a crime he didn't commit, the most newsworthy contribution of the Innocence Movement in the long run may end up being what it has taught us about the frailties of the human psyche.

Indeed, the Innocence Movement has proven to be fertile ground for forensic psychologists to study human behavior and human error. How could 10 witnesses have all said they were certain a defendant was the perpetrator of the crime, when DNA testing later proved that he was innocent? How could the police have been so convinced that a suspect was the perpetrator, while simultaneously discounting so many clues that pointed directly to his innocence? Why did a fingerprint expert testify at trial that the defendant's fingerprint was found at the crime scene, when we now know the defendant's fingerprint was not actually a match?

Loftus's important breakthroughs about human memory and eyewitness identification error are just the tip of the iceberg in terms of what the Innocence Movement has taught us about the weaknesses of the human mind. I'll give a few examples here, of which there are many.

One is the human susceptibility to "confirmation bias," which we now know contaminates forensic sciences. Confirmation bias exists when a forensic expert's pre-existing beliefs -- like a belief that the suspect is probably guilty -- skews the results and causes them to come to an inaccurate result. Much of forensic science, such as blood pattern, bite mark, tire or shoe tread, tool mark, and even fingerprint analysis, have subjective elements. In studies, researchers have found that forensic experts will sometimes flip their results (match vs. non-match) more than 50 percent of the time when their biases are manipulated before the process starts. In other words, if you tell a forensic expert that the suspect has confessed, they are much more likely to find that the tire tread in the mud at the crime scene matches the tire tread of the suspect's car. Conversely, if you tell the forensic expert that the tire tread is from someone the police want to exclude from the crime scene, the forensic expert is more likely to find a non-match.

Our television CSI heroes who always get to the truth are Hollywood myths. In fact, the problem with confirmation bias is so bad that bad forensic science has become a leading cause of wrongful conviction. It is such a problem that the National Academy of Sciences (a nonprofit which counts over 500 Nobel laureates as members) in 2009 issued a scathing report suggesting a whole range of reforms, including setting up procedures to shield forensic scientists from the influences of police and prosecutors.

Indeed, we all suffer from false memories, tunnel vision and confirmation bias in all parts of our lives, from our jobs to our interpersonal relationships. -- Mark Godsey

Related to confirmation is tunnel vision. Tunnel vision occurs when the cops develop a suspect, get excited that they might have finally solved the crime, and then become so entrenched in their belief that they ignore all the evidence of innocence that arises in their investigation. Tunnel vision is dangerous, and it happens all too often. Cops who suffer from tunnel vision and convict an innocent person aren't bad people -- they're human beings. Unless we're careful, slow down, and take the necessary precautions, we're all susceptible to this problem. Indeed, we all suffer from false memories, tunnel vision and confirmation bias in all parts of our lives, from our jobs to our interpersonal relationships.

We're also not as good as we think at telling when witnesses are lying or telling the truth. In many of the 1,200 plus cases of wrongful conviction in the Registry, the innocent defendant testified in his defense at trial, and told the jury he didn't do it. But the jury didn't believe him, and in many cases, was fooled by witnesses who we now know were flat out lying. Subsequent studies have shown that, contrary to popular belief, we humans simply aren't as good as we think at watching the nonverbal behavior of witnesses and determining whether they are being truthful.

In sum, our criminal justice system is based on the premise that we are pretty good at reconstructing facts of a crime to figure out who did it and why. We believe we can objectively and neutrally investigate, and then sort through the conflicting evidence to determine what to believe and what to discard. The Innocence Movement, with all of the psychological breakthroughs it has helped spawn, has shown this is not necessarily true. And our weak and malleable memories addressed by Dr. Loftus are just part of the problem. Experts have outlined steps that can improve the process, and reduce wrongful convictions. Making the effort to learn from the Innocence Movement would not only make our criminal justice system more accurate, but would help us better understand human vulnerabilities in everyday life.

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