Many scientific studies have shown memories can shift and distort over time. In some cases, real memories become so altered and embellished we can’t distinguish actual events from what we recall happened. What’ s more, entirely new false memories can sometimes be incorporated into our memory banks, embedded so deeply that we become convinced they actually happened, experts say.
 

The “NBC Nightly News” anchor has been called a liar for embellishing his role in the 2003 event. After apologizing, he temporarily stepped away from the nightly news.
 

But memory experts see the issue differently, noting that the well-documented story, told differently many times by Williams, offers a compelling case study of “false memory syndrome.” Over time the story changed, to the point that Williams may have believed he was the one riding in the helicopter that came under fire.
 

 “You’ve got all these people saying the guy’s a liar and convicting him of deliberate deception without considering an alternative hypothesis — that he developed a false memory,” said Elizabeth Loftus, a leading memory researcher and a professor of law and cognitive science at the University of California, Irvine. “It’s a teaching moment, and a chance to really try to get information out there about the malleable nature of memory.”
 

Many public figures have been criticized for “misremembering events.” Hillary Rodham Clinton once claimed to have been under sniper fire in Bosnia, then later admitted she had her facts wrong. Mitt Romney said he remembered a Detroit jubilee that took place nine months before he was born.
 

“Other famous people have said things that couldn’t be true, and it seems like they just were remembering it wrong,” said Christopher Chabris, co-author of “The Invisible Gorilla: How Our Intuitions Deceive Us,” and an associate professor of psychology at Union College in Schenectady, N.Y. “I think a lot of people don’t appreciate the extent to which false memories can happen even when we are extremely confident in the memory.”
 

Psychologists explain that memories don’t exist as single, complete events in one spot in the brain, but are fragments of information, stored in different parts of our mind. Over time, memories can change as the mind recombines these bits of information — sometimes with what others may say or recall about the same event — and mistakenly stores them as memories.
 

This process essentially creates a new version of the event that, to the storyteller, feels like the truth.
 

“It’s as though you’re playing the telephone game,” said Chabris. “You whisper a message and by the time it gets to the last kid it’s a completely different story than when it started.”

The scientific literature is filled with fascinating studies of researchers planting fabricated memories — of being attacked by a vicious animal, for example, or even witnessing demonic possession, The Times notes.
 

“Memory is a reconstructive process, and we are drawing on multiple sources of information,” said Steven J. Frenda, a postdoctoral research fellow at the New School for Social Research in New York. “A false memory can arise when we mistakenly attribute some other information as a memory. Whether you’ve exaggerated something in the past, or it’s something else you’ve seen or experienced, you can pull that into what you consider to be the truth.”