Sifting truth from memory: Trauma and time can alter the way we recall events

When Judge Brett Kavanaugh and Christine Blasey Ford present their vastly different recollections to the Senate on Thursday, the quality and reliability of memory itself will be on trial.

Kavanaugh has emphatically denied allegations from Blasey that he tried to rape her when they were teenagers or ever committed sexual assault against anyone. Blasey and another accuser, Deborah Ramirez, have recounted their alleged incidents with both precise detail and gaping holes.

Could Kavanaugh’s accusers be mistaken about his identity? Could he somehow have erased the experiences they allege from his memory? Or, even, could all be telling what they genuinely believe is the truth?

The biology of memory, while still far from worked out, helps to explain how vastly different accounts can emerge from a shared experience. Memory, by its nature and necessity, is selective, its details subject to revision and dissipation.

From the dizzying stream of incoming perceptions, the brain stores, or “encodes,” the sights, sounds, sensations and emotions it deems important or novel. The quality of preservation may depend not only on the intensity of emotion in the moment an event occurs but also on the mechanics of how that event is recorded and retrieved — in some cases, decades later.

“Recollection is always a reconstruction, to some extent — it’s not a videotape that preserves every detail,” said Richard McNally, a professor of psychology at Harvard University and the author of “Remembering Trauma.” “The details are often filled in later, or dismissed, and guessing may become part of the memory.”

For a trauma victim, this encoding combines mortal fear and heart-racing panic with crystalline fragments of detail: the make of the gun, the color of the attacker’s eyes. The emotion is so strong that the fragments can become untethered from time and place. They may persist in memory even as other relevant details — the exact date, the conversation just before the attack, who else was in the room — fall out of reach.

“In situations of high arousal, the brain is flooded with hormones that strengthen those things you’re paying attention to,” said Daniela Schiller, a neuroscientist at the Icahn School of Medicine at Mount Sinai. “But other details are less accessible.”

Conversely, experts suggest, there are scenarios in which someone could have committed an assault and yet also have almost no memory of it. If an assailant attaches little significance to an assault — for instance, if he doesn’t consider it an assault — his brain may only weakly encode details of the encounter.

Alcohol, even in moderate amounts, also tends to undermine the brain’s ability to encode and store sights, sounds and other details, particularly in a coherent sequence. The accounts of both women note the consumption of large amounts of alcohol; Blasey described Kavanaugh and his friend as “stumbling drunk.” Ramirez, who alleges that he exposed himself to her during a college party, said she herself was inebriated and slurring her words at the time. These memories might be fragmented or “impaired,” said Jim Hopper, a psychologist and teaching associate at Harvard Medical School and a consultant on cases involving trauma and memory.

Retrieving such experiences from memory is an equally selective task and prone to error. In biological terms, recollection is a process of both revisiting and reassembly. Recalling an event draws on some of the same areas of the brain that recorded it; in essence, to remember is to relive.

Every time the mind summons the encoded experience, it can add details, subtract others and even alter the tone and point of the story. That reassembly, in turn, is freshly stored again, so the next time it comes to mind it contains those edits. Using memory changes memory, as cognitive scientists say. For a victim, often the only stable elements are emotions and the tunnel-vision details: the dress she wore, the hand over her mouth.

“My experience is that this is the way people recall traumatic experiences,” said Esther Deblinger, a psychologist and the co-director of the Child Abuse Research Education and Service Institute at Rowan University School of Osteopathic Medicine.

The reliability of those details depends in part on when they entered the narrative. “In this case the question is, when did the accuser attach Brett Kavanaugh’s name to the incident?” said Elizabeth Loftus, a professor in psychological sciences at the University of California, Irvine. “Was it right away or did it come much later, say, in therapy?”

That answer is unclear in Blasey’s case; all that’s known is that her husband recalled that she mentioned the name Kavanaugh when she described the incident in a couple’s therapy session in 2012. (The therapist’s notes don’t identify him.) In general, Loftus said, the earliest or first memory of an event is the more reliable one.

How do victims of sexual assault forge ahead without succumbing to the weight of a terrible memory? Hopper suggested the answer may lie, in part, with how that memory is retrieved. “If you cling to an abstract, emotionally void description of an event and don’t label it ‘an attempted rape,’ then you can go for years and that’s all that will pop up,” he said. “You don’t go there with the sensory details that you have pushed away. You tell yourself, ‘I was forced into a room, I struggled and I got away.’”

But perhaps months, years, even decades after the event, an inadvertent trigger may breach the safety of the abstraction, and the reality of the memory — he was trying to rape me — may rush through, Hopper said. That realization prompts new emotions, which can reframe the narrative of the memory.

A perpetrator’s memory of the encounter is at least as prone to revision on retrieval. The encoded fragments of the event are there but typically less vivid; many relevant details may be impossible to summon, especially if the assailant hasn’t thought about the incident for years. The memory trace isn’t erased, but it can be reconfigured and supplanted.

Lingering emotions from the incident are crucial to this process. In a study of teachers and other personnel after a school shooting in suburban Chicago, McNally and colleagues found that participants’ memories of the event often changed sharply between six months and 18 months after the shooting. Some of the people who were no longer upset by the experience 18 months later recalled that they had been outside the building during the event, when in fact they’d been inside. In remembering the scene, they had physically removed themselves from it.

A similar sleight of retrieval may protect perpetrators of abuse, experts say. The human mind works to preserve a sense of moral integrity. That process is a self-serving one, allowing us to function day-to-day, tweaking our personal narrative to support who we are or want to be.

Men who commit sexual assault rarely think of themselves as assailants, Hopper said: “We tend to go with the abstract descriptions of events that make us feel less bad about ourselves and less ashamed.”

For the senators trying to sort out this explosive drama, the most important element may be timing: what happened between encoding and retrieval, and when. One thing that brain scientists have consistently found is that, once people settle on the basic “facts” of what happened, however flawed that perception, they rarely make corrections, even in face of contradicting evidence. They have their story and they’re sticking to it.

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