The state of New Jersey has been trying to help jurors better assess the reliability of eyewitness testimony, but a study reported by NPR suggests that the effort may be having unintended consequences. That’s because a new set of instructions read to jurors by a judge seems to make them skeptical of all eyewitness testimony, even testimony that should be considered reasonably reliable. In 2012, New Jersey’s Supreme Court said that in cases that involve eyewitness testimony, judges must give jurors a special set of instructions. The instructions are basically a tutorial on what scientific research has learned about eyewitness testimony and the factors that can make it more dependable or less so.
“The hope with this was that jurors would then be able to tell what eyewitness testimony was trustworthy, what sort wasn’t, and at the end of the day it would lead to better decisions, better court outcomes, better justice,” says psychologist David Yokum. Yokum was a graduate student at the University of Arizona, doing research on decision-making, when he and two colleagues decided to test the effect of these new jury instructions, using videos of a mock trial that they showed to volunteers. “We found that the instruction had an effect,” says Yokum. People who heard about the science of eyewitness testimony were much less likely to convict the defendant. That was true regardless of whether the eyewitness testimony was high-quality or low-quality, says Yokum, suggesting that the instructions simply made the jurors suspicious of all such testimony. The researchers published their research in the journal PLOS ONE.