Sometimes, police investigating a crime find that the only eyewitness they have is a child. That begs the question: Is there any difference between the eyewitness testimony of children and adults?
Dr. Steven Ceci, a child development expert at Cornell University, says yes -- children and adults imprint memory very differently based on their past knowledge of things. But that does not mean children cannot be as credible as adults.
In 2002, 5-year-old Samantha Runnion was kidnapped from outside her Stanton, Calif., home. The only witness was her 6-year-old playmate, Sarah Ahn -- who gave such a precise description of the suspect and the car he drove that he was captured days later.
However, Ceci said that the ability to relay detail varies by age. "The worst accuracy is very young kids, 2- and 3-year-olds," he said.
"They omit a lot of stuff that happens and they add stuff that didn't happen but if you look at accuracy, it starts going up, so that 6-year-olds are better than 3."
People actually max out their ability to be eyewitnesses at about age 12, and it stays constant until old age, when it starts dropping off again, Ceci said.
"The main ingredient which drives the memory difference is how much they know about the event before they experience it. So the 3-year-old's not very good at recalling what he saw because he doesn't have the script the adults have about what happens in a filling station," he said.
Ceci also said there are times when a child can be a lot more accurate than an adult.
"Because of all our knowledge we may see things that aren't there," he said. "When you show adults videos of kids in college taking an exam and someone asks the time, adults see cheating. The young kids don't."
However, Ceci warned that people relying on the eyewitness testimony of children need to be careful about how that information is obtained.
Sometimes children create false memories. In the 1980s, children who had attended McMartin preschool outside Los Angeles accused their caretakers of sexually abusing them.
It turned out the stories the kids told were not true. But Ceci said the kids in this case, and similar subsequent cases, were not exactly lying.
The kids were repeatedly asked leading questions, he said, and "their memories have been altered by the incessant, suggestive interviews they were subjected to."
Interviewers can ask the wrong questions, Ceci said. "They pursue the child, often relentlessly, with leading questions and suggestions so under those situations, if a child's memory is weak or non-existent, you can implant a false memory," he said.
If you have a man in a police uniform interviewing children, and then a man in a janitor's uniform interviewing children, "the person in a janitor's uniform will have higher accuracy," Ceci said.
Children sometimes wind up "trying to provide you with what they think you want them to say," he said -- especially when the adult is an authority figure.
The children don't feel as obliged to follow a person dressed as a janitor, he said.
Ceci said children -- even 3-year-olds -- can be credible witnesses if their memory is not tainted by leading questions. "They may not tell you a lot, but what they tell you, you can go to the bank with. It'll be highly accurate," he said.