Emotions, especially those provoked by negative events, a new research has revealed, can trigger inaccurate memories. And it gets worse with adults than children.
The findings contradict prevailing legal and psychological thinking and have implications for the criminal justice system, said Valerie Reyna and Charles Brainerd of Cornell University.
The study shows that experiences that stimulate negative emotions are very bad for the accuracy of children's memories, but even worse for the accuracy of adults.
"We found something different than what leading theories of emotional memory in adults say," Brainerd said.
"By manipulating the emotional content of word lists, we found that materials that had negative emotional content in fact produced the highest levels of false memory," he said.
Children ages 7 and 11, and young adults ages 18 to 23, were shown lists of closely related emotional words - such as pain, cut, ouch, cry and injury.
In each list some related words - such as hurt- were left out. When asked to recognize words from the list, respondents would often mistakenly remember hurt as one of the words. These mistakes allowed researchers to determine the level of emotion-induced false memory at each age.
The implications of the findings are profound for the U.S. legal system.
"In the great preponderance of legal cases, the only evidence that's determinative is what people say happened," said Brainerd.
"That's it. So the question of the conditions under which your memory of events is distorted is the most fundamental question about the reliability of evidence - because it is most of the evidence.
"In the law, you're dealing with events that are emotional. So the question of whether or not the emotional content of experiences that you're trying to remember screws up your memory is a really big question," he said.
The researchers, also co-authored the 2005 book 'The Science of False Memory.'
The findings were published in the Journal of Experimental Child Psychology.