How Brain Science Can Help Explain Discrepancies in a Sexual Assault Survivor's Story

05/22/2015 11:42 am ET | Updated May 22, 2016
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"I believe that you believe something happened to you." The young woman repeated the detective's statement to me again. It had been the detective's response to her question of whether he believed her account of the brutal sexual assault she had experienced the past weekend.

As a counselor on the local rape crisis hotline, it was not the first time I had heard such a demoralizing story of an individual's attempt to report sexual violence to law enforcement. Because her story had been disjointed, and she had stumbled over several sections of it, the detective had thought that she was confabulating, creating a crime where none had occurred.

When I hear of this dynamic, my thoughts often turn to the neuroscience of trauma. The brain's response to trauma is complex, and human behavior in response to trauma, particularly sexual violence, is not well-understood but recent research does offer some important insights.

The rate of false report in sexual violence is actually low, estimated by most studies to be around 7 percent (to compare, this is considerably lower than the rate of insurance fraud). Moreover, research shows that sexual violence is in fact underreported: Many more incidents of violence occur than are reported to law enforcement or other legal authorities. Studies show that there are many factors that may predict whether an individual will report, including level of acquaintance with the perpetrator and whether alcohol was consumed.

Taken together, research findings on the factually low rate of false report and on the underreporting of the crime itself demonstrate a clear contradiction in people's conceptions of sexual violence and that violence in reality. There is a mismatch between media portrayals of "ideal victims" -- young, sober women attacked at knifepoint in parking lots at night -- and research on real-world victims -- nearly three-quarters of whom know the perpetrator (rising to nearly 90 percent on college campuses) and only 7 percent of whom were attacked with a firearm, knife or other weapon.

This kind of misunderstanding of an individual's experience of sexual assault is heartbreakingly common. A high school student's report of sexual assault was viewed skeptically by an elected lawmaker, who stated on the public record that "some girls, they rape so easy." More recently, a fan base made it clear that it did not believe a woman accusing a sports hero of rape, and that she was making the story up for attention.

Why are victims so often not believed? A large amount of this disbelief may be linked to the behavioral patterns of victims themselves, which can vary widely from case to case and often include behaviors of which the average police detective would be skeptical. To understand these patterns, it is helpful to look at how the brain and body respond to stress and trauma, such as that experienced during sexual violence.

A relatively new area of the literature on human response to trauma, particularly the trauma experienced during sexual violence, is that of "tonic immobility." Defined as self-paralysis, or as the inability to move even when not forcibly restrained, tonic immobility has long been studied in non-human animals as the "freeze" response to extreme stress. Recently, it has been observed in the laboratory as a stress response in humans, as well. This finding explains the reaction of many victims of sexual violence, who report that they felt like they could not escape, even when no weapon was present.

Additionally, due to an entire cascade of hormonal changes, which includes oxytocin and opiates, associated with pain management, adrenaline, commonly associated with "fight or flight," and cortisol, functional connectivity between different areas of the brain is affected. In particular, this situation affects pathways important for memory formation, which means that an individual can fail to correctly encode and store memories experienced during trauma. While an individual generally will remember the traumatic event itself (unless alcohol or drugs are present in the system), these memories will feel fragmented, and may take time to piece together in a way that makes narrative sense.

Behavioral patterns in individuals who have experienced sexual violence mirror those seen in other traumatized populations, like combat veterans. This pattern of symptoms, known as post-traumatic stress disorder, or PTSD, can include emotional numbness, intrusive memories of the traumatic event, and hyperarousal (increased awareness of one's surroundings, or constantly being "on guard").

Research shows that the majority of individuals who experience sexual assault demonstrate at least some of these symptoms of PTSD immediately after the assault and through the two weeks following the assault. Nine months after the assault, 30 percent of individuals still reported this pattern of symptoms. Overall, it is estimated show that nearly one-third of all victims of sexual assault will develop PTSD at some point in their lives.

These findings are complicated by the fact that the response of any given person to trauma can look extremely different, based on previous life experiences and health factors. Research has found that cognitive variables, such as perceived negative responses of other people and poor coping strategies, were significantly linked both to development of PTSD and severity of PTSD. In another study, lower cortisol levels as measured in the emergency room have been related to increased risk for the development of PTSD. In other words, a maladaptive version of nature/nurture is involved in individuals' responses to trauma.

As with many questions related to health, it is difficult to pinpoint the cause: existing neurobiological and psychosocial risk factors, such as mental illness, can contribute to the development of PTSD, and PTSD can lead to other health problems. There is no hard and fast rule of victimology: every individual who experiences sexual violence will respond differently.

Therefore, the detective who was unable to believe the story told to him by my crisis caller was likely misinterpreting the discrepancies in her story as lies, rather than as her brain's responses to extreme trauma. Best practices now suggest that officers wait at least two sleep cycles, generally 48 hours, before interviewing a victim of sexual violence. Additionally, the interview should be handled in a victim-centered manner, not as an interrogation. Research-informed practices have the potential for not only better outcomes for survivors of sexual violence, but also for reporting and prosecution rates for our legal system.


Kathryn Gigler is a doctoral candidate studying the cognitive neuroscience of learning and memory at Northwestern University. She also serves as director of the Women's Center at Elizabeth City State University.

This post is part of a HuffPost Science series exploring the surge of new research on the human brain. Are you a neuroscientist with an insight to share? Tell us about it by emailing

Need help? In the U.S., visit the National Sexual Assault Online Hotline operated by RAINN. For more resources, visit the National Sexual Violence Resource Center's website.