National experts on eyewitness testimony said it’s not surprising that there would be so many conflicting accounts — particularly of a chaotic crime scene.

Memory, they say, isn’t like a video recording. Our brains encode only fragmented images of events, which are instantly malleable.

A quick, violent event — particularly one involving a gun — can be one the most challenging scenarios for an eyewitness to fully and accurately recall.

A phenomenon called “weapon focus” becomes one of the biggest obstacles to seeing details of an event and remembering them as a whole.

“People tend to focus on the weapon to the exclusion of other variables at the scene,” said John DeCarlo, a professor at John Jay College of Criminal Justice. “It doesn’t distort what really happens, but it takes attention away from other things.”

Brian Cutler, eyewitness expert and professor at the University of Ontario, Institute of Technology, said the faster and the more stressful an event, the more difficult it is for people to recall it.

“The less time you have, the less effective you are at encoding it,” Cutler said. “Extreme stress also debilitates memory. If you perceive danger why would you stop and stare?”

As a result, Gary L. Wells, an internationally recognized expert on eyewitness memory, said, our brains tends to record “in snippets” and then fills in the blanks later – and often with false information.

“The brain doesn’t like empty spaces,” said Wells, who is a professor of psychology Iowa State University. “We deduce things that may have happened. Sometimes it is just outright guesses that are made. Those deductions and guesses then become part of our memory.”

This all happens without us knowing it, and can begin within minutes of the events, but accelerates as time goes by, Wells and DeCarlo said.

In the case of Michael Brown’s shooting, eyewitnesses memories’ could have morphed based on what other eyewitnesses said they saw — especially since many of their accounts were being broadcast on television before they provided their account to police.

“Many reports were flying around and that could contaminate other witnesses,” said Wells. “You maybe didn’t see a surrender, but someone else did, and suddenly that is part of your reconstruction of what you think happened there.”