Few things make a story more believable than eyewitness accounts. That's great for prosecutors, but potentially terrible for the truth: There's a mountain of data cataloguing how bad eyewitnesses are at identifying the people who actually committed a crime. Now, researchers find, one state's attempt to keep the power of dubious testimony in check—essentially, reminding jurors to remain skeptical—works. Actually, it might work a little too well.
Psychologists have plenty of reasons to question eyewitness testimony. For one thing, telling people apart from distances of a few hundred feet is pretty much impossible. But even if we could identify criminals in the moment, memory is a fickle creature, and when a case goes to trial, witnesses may unintentionally fill in or adjust details to suit the circumstances. Under the right circumstances, it's even possible to convince people that they themselves had taken part in events that never transpired.
Stricter scrutiny revealed a lack of nuance in jurors' votes.
What's a court to do? One approach is to re-write the standard for admissibility of eyewitness identifications. But in 2012, New Jersey courts adopted a quicker solution: Basically, reminding jurors to be extra wary. "Eyewitness identification evidence must be scrutinized carefully," New Jersey judges now instruct juries, reminding them "that human memory is not like a video recording that a witness need only replay to remember what happened." The instructions continue with a crash course in psychology and some examples of the ways our memories can deceive us.
Whether those instructions might make for more sophisticated jurors, however, remains unclear. To find out, University of Arizona legal scholars Athan Papailiou, David Yokum (now a member of the White House Social and Behavioral Sciences Team), and Christopher Robertson recruited 335 people for an experiment in justice. After first watching testimony about a defendant charged with killing a convenience store clerk, then reading either standard jury instructions or the enhanced New Jersey instructions, participants had a simple choice: guilty or not guilty?
At first glance, jury instructions highlighting the messy nature of memory had the intended effect: About one in 10 who got the enhanced instructions voted to convict, compared with one in four of those who heard the standard version.
But stricter scrutiny revealed a lack of nuance in jurors' votes. When the researchers put together the testimony video, they actually made two videos, one emphasizing reasons to trust a witness's memory, and one raising red flags. Theoretically, enhanced instructions should give jurors the tools they need to distinguish strong testimony from weak. In fact, all it did was make them skeptical of eyewitnesses—reading the enhanced New Jersey instructions cut the number of guilty votes roughly in half, regardless of the testimony's strength.
"The result is suboptimal: the New Jersey instructions will likely increase the rate at which guilty defendants are exonerated," the team writes in PLoS One. "Yet it might still be an improvement over the 'standard' instruction, at least if one agrees with Blackstone's argument"—better 10 guilty people go free than one innocent suffer.
Quick Studies is an award-winning series that sheds light on new research and discoveries that change the way we look at the world.