"The real world of our memory is made of bits of true facts, surrounded by holes that we Spackle over with guesses and beliefs and crowd-sourced rumors. On the dot of 10 on Wednesday morning, Anthony O’Grady, 26, stood in front of a Dunkin’ Donuts on Eighth Avenue in Manhattan. He heard a ruckus, some shouts, then saw a police officer chase a man into the street and shoot him down in the middle of the avenue.
Moments later, Mr. O’Grady spoke to a reporter for The New York Times and said the wounded man was in flight when he was shot. “He looked like he was trying to get away from the officers,” Mr. O’Grady said.
Another person on Eighth Avenue then, Sunny Khalsa, 41, had been riding her bicycle when she saw police officers and the man. Shaken by the encounter, she contacted the Times newsroom with a shocking detail.
“I saw a man who was handcuffed being shot,” Ms. Khalsa said. “And I am sorry, maybe I am crazy, but that is what I saw.”
At 3 p.m. on Wednesday, the Police Department released a surveillance videotape that showed that both Mr. O’Grady and Ms. Khalsa were wrong.
Contrary to what Mr. O’Grady said, the man who was shot had not been trying to get away from the officers; he was actually chasing an officer from the sidewalk onto Eighth Avenue, swinging a hammer at her head. Behind both was the officer’s partner, who shot the man, David Baril.
And Ms. Khalsa did not see Mr. Baril being shot while in handcuffs; he is, as the video and still photographs show, freely swinging the hammer, then lying on the ground with his arms at his side. He was handcuffed a few moments later, well after he had been shot.
There is no evidence that the mistaken accounts of either person were malicious or intentionally false. Studies of memories of traumatic events consistently show how common it is for errors to creep into confidently recalled accounts, according to cognitive psychologists.
“It’s pretty normal,” said Deryn Strange, an associate psychology professor at John Jay College of Criminal Justice. “That’s the hard thing to get our heads around. It’s frightening how easy it is to build in a false memory.”
A leading researcher in the field of witness memory, Elizabeth Loftus of the University of California, Irvine, said there was ample evidence that people found ways to plug holes in their recollections.
“If someone has gaps in their narrative, they can fill it in with lots of things,” she said. “Often they fill it with their own expectations, and certainly what they may hear from others.”
These are not the knowingly untrue or devious statements of people who are deliberately lying. False memories can be as persuasive as genuine ones, Dr. Loftus said: “When someone expresses it with detail and confidence and emotion, people are going to believe it.”
Said Dr. Strange, “It is surprising to the average person how quickly memories can be distorted.”
That was certainly Ms. Khalsa’s response.
“I feel totally embarrassed,” she said on Thursday, after having seen the video.
She now believes that she saw the initial encounter and then looked away, as she was on her bicycle. In that moment, the man began the attack, which lasted about three seconds until he was shot. “I didn’t see the civilian run or swing a hammer,” she said. “In my mind I assumed he was just standing there passively, and now is on the ground in handcuffs.”
“With all of the accounts in the news of police officers in shootings, I assumed that police were taking advantage of someone who was easily discriminated against,” she added. “Based on what I saw, I assumed the worst. Even though I had looked away.”
Her own certainty was gone, Ms. Khalsa said.
“It makes me think about everything in life,” she said."