The amount of ambiguous evidence in the Zimmerman trial is alarming, and undoubtedly the reason he was ultimately determined not guilty. One thing that’s for sure is that someone was yelling in the background of one of the 911 calls made by a nearby resident, and both the defense and prosecution attempted to use the screaming to enhance their case. One would expect that the screamer was the one being attacked, so naturally the defense brought in people to testify that the screams were Zimmerman’s, while the prosecution tried to prove that they were Martin’s.
The first sentence of the last paragraph of this Huffington Post article reminded me of the fallibility of human memory:
Ultimately, there are only two people who ever knew for sure who was screaming for his life that fatal night. One of them is dead, and the other has been acquitted in his killing.
Jermaine Spradley, the author, says that Zimmerman and Martin are the only people “who ever knew,” and I think that’s a really important word choice. I suspect that Zimmerman probably doesn’t know any more who was screaming. He probably believes that he knows he was the one screaming (or maybe he doesn’t even believe this), but I’m not sure it’s possible for his memory to have remained objective and accurate after almost a year and a half has passed since the incident and he has undoubtedly recalled the event many times.
This study by Barbara Tversky and Elizabeth Marsh is one of many that reveals the biasing effects of retelling a story through a biased viewpoint. Participants had to read a story, write a biased letter about one of the characters, and later remember the story again. In 5 separate experiments, the researchers found that not only did the letters contain more details and elaborations that were relevant to the character they were writing about, but the perspective they took in writing the letter affected the amount of information they recalled, and the errors they made in both recall and recognition tasks (the errors tended to favor the character whose perspective they wrote about).
Once we’ve retold a story, especially one with a bias towards one character, our memory of the event is actually altered such that we recall the event differently and even respond differently to recognition questions about the situation, in which we don’t have to generate the facts ourselves.
It’s kind of haunting to think that, as Spradley wrote, there were only two people who knew who was screaming. Now, I would guess, there are none.