Contaminated Memories


I was certain of my assailant’s identity. Why didn’t an alarm bell go off?

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I was certain of my assailant’s identity. Why didn’t an alarm bell go off?CreditCreditDebra Tolchinsky

By Debra Tolchinsky

Ms. Tolchinsky is a filmmaker.

June 25, 2019

I began exploring the intersection of memory and law after hearing the story of Penny Beerntsen, who was assaulted while running on a beach in 1985 — and who misidentified her assailant in the subsequent investigation. There’s a term for what she experienced: “memory contamination.” It’s when investigators influence an interview with a subject, resulting in inaccurate information.

Moved by Ms. Beerntsen’s account as well as her openness about it, I wanted to help share her story more broadly. (Her case became well known when her misidentified assailant’s account was featured in the series “Making a Murderer;” the show does not include Ms. Beerntsen’s perspective.) We started working together on this documentary project, in which we tried to capture the concept of memory contamination in a visual way.

Memories like Ms. Beerntsen’s are more widespread than we’d like to think. After I spent an afternoon on the beach where her assailant had stalked her, a memory of my own resurfaced. At 16, I had also been stalked on a deserted beach. Though I managed to escape, the similarity to Ms. Beerntsen’s account made me wonder: What if I hadn’t gotten away? If I tried to describe my stalker, what would I recall? Could I pick him out of a police lineup?

Describing an assault can induce additional trauma for survivors. Despite these challenges, violent offenders are often accurately identified, when an eyewitness picks out the perpetrator — and protects the community from future offenses. But human memory is inherently flawed, and eyewitness misidentification plays a role in two-thirds of convictions overturned through DNA testing nationwide.

Although most of us trust our recollections, cognitive scientists like Elizabeth Loftus have shown that suggestions and post-event information can modify memories. Factoring in trauma, as well as the suggestive tactics investigators are sometimes incentivized to employ to close their cases, memory contamination becomes very plausible. We are more susceptible than we would like to think.

Eyewitness testimony is particularly powerful precisely because the emotion fueling it is often completely genuine. The person delivering the testimony may believe in its fidelity regardless of its accuracy. But as Ms. Beerntsen’s case reminds us, it’s devastatingly easy for a witness to misidentify, so we need safeguards to ensure that those convicted are genuinely deserving.

Debra Tolchinsky is a documentary filmmaker and associate professor of radio-TV-film at Northwestern University. This Op-Doc is part of her forthcoming documentary feature “True Memories and Other Falsehoods” in development with Kartemquin Films.

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