In Doubt: The Psychology of the Criminal Justice Process
by Dan Simon .
Harvard University Press, 2012 ($45)

Ten years into serving a life sentence for the rape of Jennifer Thompson, Ronald Cotton stepped out of prison a free man. It took that long for DNA evidence to exonerate Cotton, refuting a weak case built mostly on eyewitness accounts.

According to Simon's new book In Doubt, despite advances in DNA forensic technologies, eyewitness testimony remains the most common way to nab criminals in the Anglo-American justice system. The problem, however, is that our mind often subconsciously twists the evidence to coincide with our biases, and we end up incarcerating innocent people. Simon, a professor of law and psychology at the University of Southern California, says that the false conviction rate, based on exoneration data from capital murder cases, is estimated to be near 5 percent, although that figure represents only a fraction of those wrongly imprisoned.

Eyewitness testimony boils down to how well the witness remembers the event. Studies have shown that a victim of a crime may remember a specific piece of information from the horrid event, such as the attacker's jacket or a strange smell, but fail to recall other details. Investigators are left with a weak profile of the perpetrator. In Cotton's case, the victim initially chose two men from the lineup, and only after repeated questioning from investigators could Thompson say Cotton was her assailant.

The human mind is also bad at encoding the details of a face, which means that an eyewitness may struggle to identify a suspect, even immediately after an event. Researchers have confirmed this observation, revealing that pedestrians do not realize they are talking to a different stranger midconversation after a diversion allows one stranger to swap in unnoticed for another.

As the investigation wears on, witnesses and victims relive the emotional events of the attack. This memory loop, in which recollections are retrieved and then reencoded, offers opportunities for bias to seep into the victim's personal account. Surprisingly, no matter how many opportunities there are for memories to morph throughout a trial, witnesses still consider their memories unshaken. In one study, 90 percent of subjects reported they were confident in their memory recall, when in fact only 60 percent of them were accurate. To remedy these problems, Simon calls for investigators to record all interviews to standardize the way they interact with victims, witnesses and suspects. He recommends that juries be instructed about bias in the courtroom. Such efforts are more likely to guide those involved to the underlying truth.

In In Doubt, Simon offers a compelling, though dense, overview of our flawed justice system and our imperfect brain. He backs up every claim with research, which makes the solutions he presents seem viable. Overall, Simon's book can help us avoid our mental pitfalls and see the truth more clearly.