Force Science Institute Details Reasons For Delaying Interviews With OIS Survivors

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As you know, the Force Science Institute in its Certification Course (visit www.forcescience.org for more details) and in public statements advocates that officers who have been involved in shootings or other high-intensity events should be allowed a recovery period of at least 48 hours before being interviewed in depth about the incident by IA or criminal investigators.

An increasing number of departments are accepting this view, but some agencies still maintain that taking an officer’s statement as soon after the incident as possible–even before the officer is allowed to go home–better assures an accurate and comprehensive recall of what happened because the occurrence is freshest in mind at that point.

Recently Force Science News sat down with FSI executive director Dr. Bill Lewinski to explore this persistent controversy. Here are highlights of that conversation, explaining in detail why the Force Science Institute supports delayed interviewing.

“It’s true that during a delay, some contamination of an officer’s memory can possibly occur,” Lewinski acknowledges. “But the overall benefit of waiting while he or she rests and emotionally decompresses far outweighs any potential loss of memory. A day or two between the event and the interview will have no significant effect on reducing recall. In fact, the opposite is true. Delay enhances an officer’s ability to more accurately and completely respond to questions.

“This is the general conclusion from some 20 years of scientific research on sleep and memory consolidation. And it is the position supported by the Police Psychological Services Section of the International Assn. of Chiefs of Police, which is comprised primarily of psychologists and other experts on human behavior who are intimately familiar with the law enforcement experience. The Psych Section recommends a two- to three-day delay between the event and the interview.”


The Force Science Institute believes that the controversy stems from a failure to fully comprehend the unique dynamics of a sudden, high-stress, potentially life-threatening episode.

“When the average person thinks about memory,” Lewinski says, “they may think in terms of taking exams, let’s say, and of the need to tap their memory of a subject as soon after studying as possible for maximum recall. But memory of a high-impact critical incident that an officer has personally and intimately experienced is far different than the memory of a poem or facts for an exam on constitutional law.

“Here we’re talking about memory of an event that may occur suddenly, require time-pressured decision-making, and be action-packed, visually and behaviorally complex, rapidly evolving, and perhaps life-threatening.

“The emotional and cognitive reactions to these factors separate that kind of circumstance dramatically from the memory experiences of most people.”


First, Lewinski points out, there’s the effect of adrenaline on memory.

“This has literally been studied for generations,” he says. “Most studies don’t even come close to exposing the research subject to the level of adrenaline surge an officer experiences in a gunfight or other life-threatening circumstance.

“Yet even so, findings from both animal and human studies suggest that when emotional arousal and adrenaline are involved, it takes some time after an incident for the experience to become settled, deeply entrenched, and consolidated in the brain. This adrenaline effect can extend, conservatively, up to a dozen hours or more after the incident, and some research suggests that memory consolidation for extremely stressful and fearful encounters can continue out to a week afterward. This extensive period of post incident consolidation is one of the reasons for the frequently very vivid recall of traumatic incidents. Usually any errors in recall about the event are not in the core but on the peripheral details and can be attributed to visual and attentional focus issues in the incident and not to post-incident contamination or erosion of the memory during the period of consolidation.

“We could say that emotion-arousing events, in a sense, delay forgetting.”


Besides adrenaline, there’s the influence of sleep.

“Here, there are two questions to address,” Lewinski says.

“1) Does rest–especially REM or deep sleep–facilitate memory consolidation for the type of event in which an officer is usually intently focused and scrambling to control a situation and survive?

“And 2) What is the optimal time and process to evoke or tap that memory?

“Our brains do not rest when we are asleep,” Lewinski continues. “They are active in processing and consolidating our day’s activities and embedding memories.

“The research linking REM or slow-wave (deep) sleep to enhanced memory consolidation is robust. Such sleep has a positive impact on both procedural and episodic memory.

“Procedural memory is memory for a skill or an automatic motor activity, such as playing a musical instrument, shooting baskets, or building trigger-pull skills. Practicing a skill and then literally ‘sleeping on it’ will typically result in an improved performance after you wake up. Two decades of scientific research support this enhancement.

“Episodic memory is memory of an event, an episode. Here 10 years of research supports the finding that consolidation of episodic memory appears to occur throughout a full sleep cycle, with the first three to four hours of sleep being especially beneficial.”


“There is little doubt that incidents of an intensely personal and emotional nature can be more accurately remembered and reported on after a good sleep cycle,” Lewinski says. “But–after a critical law enforcement incident, quality REM and slow wave sleep generally occurs two nights out, not the night–or the time of sleep — immediately following a gunfight or other high-stress situation.

“Just as a person who is engaged in an argument or some interpersonal conflict will leave the scene and replay or review the incident as they’re driving home, including all the emotional elements that accompanied the conflict, so will officers do the same thing after a shooting. A high level of arousal will inhibit the officer’s ability to emotionally disengage and fully rest during the first sleep cycle.

“That’s why, depending on the officer’s condition and the complexity of the circumstances, the Force Science Institute recommends a 48-hour delay, accommodating two sleep cycles, as a reasonable rule of thumb before trying to retrieve memories related to a high-stress event.”


Beyond improving memory, a delay aids an officer’s emotional decompression, Lewinski explains.

“Stress from a shooting or other emotional event not only impairs sleep but also affects cognitive processing,” he says. “Individuals who are distraught or fatigued have a diminished ability to understand the meaning and complexity of questions and to accurately and precisely express themselves.”

There’s an ironic component to deadly force encounters that often heightens the stress of these incidents and compounds communication problems, Lewinski says. He explains:

“Most officers readily answer affirmatively to the question, ‘Can you use deadly force?’ But the truth, from my experience, is that most officers have not really considered the possibility that they may actually have to take someone’s life or that they themselves could be seriously injured or killed on the job.

“Generally, officers experience some basic level of distress at having taken someone’s life. But I’ve found two other factors in force encounters to be much more influential in creating distress.

“First, there’s the sudden confrontation with a reality they haven’t thought much about: coming face to face with a person who has the intent and ability to kill them and is acting on that in the immediate moment. And then there’s the realization that the officer may have little or no ability to change what is happening or the eventual outcome. For instance one officer shot and killed a young teenage girl in an incident. The discrepancy between the type of deadly force incident he had imagined and prepared for and the reality of the incident that actually occurred, where he had to shoot to defend himself could never be altered. In his mind she controlled everything and nothing he tried kept him from having to shoot her. It is ironic but he felt vulnerable and victimized.

“The powerful emotions and the flood of hormones that accompany such emotions in circumstances like this greatly influence and magnify the degree of distress experienced. Memory, attention, and critical thinking can be significantly impaired. Combine that with probable physical fatigue from an extended period of wakefulness and you have an officer who could be cognitively operating as if legally intoxicated during an interview that’s conducted immediately post-incident.

“The Force Science Institute recognizes that an extended rest period will strengthen an officer’s ability to respond in what likely will be the most important interview of his life–and one of the most important interviews for his department as well.”


If there is any memory loss or distortion during the delay period, Lewinski says it most likely can be “tempered” by using “one of several interview techniques to facilitate recall.” He mentions, for example, “context reinstatement,” which Force Science Certification Course graduates will recognize as an element of the Cognitive Interviewing protocol that is taught in the class.

For this memory prompt, the officer is encouraged to mentally immerse himself back into the scene, emotionally and physically, and then begin to describe what happened to the interviewer. This, combined with reviewing video of the event or walking through the location, can be very effective in retrieving “lost” memories, Lewinski says.


Critics of postponing an interview until the involved officer is well rested sometimes argue that a delay provides an officer with an “unfair” luxury that is not given to civilians who are arrested and then promptly interrogated.

“In the eyes of Force Science, this comparison is invalid,” Lewinski declares. “In reality, criminal suspects don’t ever have to give a statement if they don’t want to. They often can bond out, go home and watch video of their incident on the local news and even confer with their involved buddies about what happened–opportunities that often are denied officers.

“Law officers are specially selected and trained and act under the color of authority. In a deadly force encounter, they are forced to make a decision and take an action on behalf of the society they are sworn to protect. When their decisions and actions are reviewed, they deserve an unbiased and competent investigation, and that includes a protocol that best allows them to fairly represent themselves in explaining what happened.”

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