The Familiarity Bias: Why Your Best Trained Instinct Can Also Be Your Biggest Liability

Every officer builds a kind of mental shorthand over the course of a career. Certain movements, certain postures, certain cues start to register as meaningful before an officer has consciously processed them at all. That shorthand is familiarity bias: a mental shortcut built from repeated exposure to similar calls, similar behaviors, and similar situations. It’s a form of pattern recognition, and it exists to help officers make decisions faster, under conditions where speed often matters.

Implicit guidance isn’t limited to what an officer learns at the academy. It’s the accumulated sum of an entire life, with law enforcement training layered on top of it, and familiarity bias is one of its most visible, day-to-day expressions.

It’s tempting to treat “bias” as a word that only belongs in a disciplinary conversation, something to be rooted out and eliminated. That’s not the right frame here, and it’s not a particularly useful one either. Familiarity bias is a byproduct of training working exactly as intended: repeated exposure builds recognition, and recognition builds speed. The more useful question isn’t whether the shortcut exists. It’s how the shortcut works, when it serves officers well, and when it quietly starts working against them.

That nuance was the focus of a recent Vector Solutions webinar, Preparing Officers for the Community they Serve, featuring Sgt. Dan Greene (ret.), Executive Director at the National Association of Field Training Officers (NAFTO), Autumn Timmins, Founder and President of Preston’s Pursuit for Acceptance (PPA), and Lt. Chris Timmins (ret.), Co-Founder & Vice President of PPA. The discussion was moderated by Sgt. Doug Kazensky (ret.), Senior Solutions Engineer at Vector Solutions.

Drawing on their combined experience, they discussed how familiarity bias and implicit guidance shape split-second decisions in the field, when that trained instinct serves officers well, and when it can lead them astray.

The Instinct That Keeps Officers Safe

Officers rarely get the luxury of a slow, methodical read on every situation, and schema-based recognition, spotting a pattern quickly based on prior experience, exists precisely because it lets officers act fast under real, constant constraints.

Recognizing patterns quickly is a skill, and like any other skill, it gets built deliberately, over years, through repeated exposure to the job. The catch is that what counts as a “normal” pattern shifts over time, and training has to shift with it.

“The day I got hired, someone’s bulge underneath their t-shirt was a pager. In 2026, it’s probably a phone,” Sgt. Greene shared as an example.

The underlying behavior of an object-shaped bulge under clothing hasn’t changed at all, but what that bulge most plausibly represents has changed considerably. If training doesn’t keep pace with that shift, the pattern recognition officers rely on ends up running on outdated assumptions, which can be dangerous for all involved.

At its core, familiarity bias is an efficiency tool, built for a job that constantly requires making fast decisions under pressure. Used well, it lets experienced officers pick up on things a rookie might miss entirely, and it does real work keeping people safe. However, making sure the efficiency tool gets recalibrated as often as the world it’s trying to interpret is imperative to keep it from becoming a hindrance.

When the Same Instinct Works Against You

Efficiency and accuracy are not the same thing, and that distinction is where familiarity bias starts to create real risk.

“It doesn’t necessarily help us make the best decision at the moment, but it does help us make the most expedient decision,” Sgt. Greene said.

For officers, often the fastest read and the correct read are the same thing, but that isn’t always the case, and an officer moving on instinct alone has no built-in way to tell the difference in the moment it matters most.

The mechanism behind this is straightforward. Officers are trained hardest, and most repeatedly, to recognize threat indicators, and that training doesn’t switch off just because a particular piece of ambiguous behavior doesn’t actually indicate a threat.

Ambiguous behavior tends to default to the most heavily trained pattern available, not necessarily the most accurate one.

The fix for that isn’t to strip away pattern recognition. Instead, it’s to build in a pause before the first read becomes the only read.

“Someone is avoiding eye contact, they’re upset and agitated, you’re thinking pre-attack indicators, right? And that may be true. But if you have the benefits of time and space, you have the benefit of being able to slow down and consider an alternative hypothesis of what may be going on here,” Sgt. Kazensky said.

The goal isn’t to have officers second-guess every instinct or decision they make, it’s just to make the pause itself a trained reflex, so that holding two possibilities in mind for a few extra seconds becomes as automatic as the initial pattern recognition already is.

However, this only works when officers have the benefit of time and space to use it. Not every call allows for that kind of pause, but when a call does allow it, using it is what separates the most expedient decision from the best one.

Same Behavior, Two Different Stories

A case study shared by Lt. Timmins shows just how much a single additional question can change. During a DUI task force, an officer became convinced an individual was impaired after they performed poorly on standardized field sobriety tests.

“The person a hundred percent believed that this individual was impaired,” he said.

However, there was no odor of alcohol, no obvious signs of consumption, no clear indicators beyond the poor test performance itself. Standard protocol already included asking about medical conditions that might affect the results, and that question had already been asked and answered. However, Lt. Timmins asked a slightly broader question:

“Outside of conditions, have you ever been diagnosed with anything else?”

It’s a small variation on a question that had technically already been covered, but it was open-ended in a way the earlier version wasn’t. The individual has autism.

The blood test came back completely clean, confirming the individual was not impaired.

That gap between what the field sobriety test performance seemed to indicate and what was really happening is familiarity bias. The officer had been trained, correctly, to read poor performance on standardized field sobriety tests as a strong indicator of impairment, because in the overwhelming majority of cases, it is. It just wasn’t the only possible explanation for what was in front of them.

“Had the officer slowed it down and asked some more clarifying questions, the situation might have just a conversation at the side of the car,” Timmins said.

Seen From the Other Side

Behaviors like avoided eye contact, non-compliance with verbal commands, and visible agitation can look and feel entirely different from the other side of that encounter. As shared by Timmins, a driver anxious about being pulled over may exhibit similar behavior, particularly if they are neurodivergent.

“It’s simply because the systems in his body are shutting down, and he’s overstimulated, and he’s trying to cope, but, his body’s not cooperating,” she said, describing how her son Preston, who is on the autism spectrum, may react in during a traffic stop, despite being raised around men and women in uniform his whole life.

Timmins also discussed how stimming, a common self-regulating behavior for people on the autism spectrum, can be misinterpreted.

“It’s a coping mechanism. It’s a means to regulate themselves,” she said.

A behavior that might read as agitation or threat from the outside could be an attempt to calm down, not a step toward escalation. The behavior officers are trained to flag and the behavior that’s occurring can be the exact same movements, read through two completely different lenses.

This is where familiarity bias and the second-hypothesis habit meet directly. Nothing about the underlying behavior changes based on which explanation is correct. What changes is whether an officer has been trained to consider more than one explanation before responding, and whether the situation allows the time to do it.

That gap points directly to what training needs to do differently.

• Build “alternative hypothesis” prompts into scenario-based training, not just threat-recognition drills.
• Explicitly teach the distinction between the most expedient decision and the best decision, and when each one is the right call.
• Add a clarifying question to standard protocols, anywhere a diagnosis or condition could plausibly mimic the indicators officers are trained to look for.
• Treat this as recalibrating implicit guidance over time, not discarding the instincts officers have already built through years of training.

Who delivers this kind of training matters as much as the content itself.

Training on this topic is itself subject to the same shortcut it’s trying to address, and an instructor without a working understanding of police culture and officer safety can end up teaching officers to override good instincts rather than to pair them with a second look.

Familiarity bias isn’t the enemy. It’s an efficiency tool, built through years of repeated exposure to the job, that needs periodic recalibration as situations, populations, and context evolve. The goal isn’t to remove the instinct that keeps officers moving quickly and safely through a shift. It’s to build in the pause that lets a second hypothesis surface before the first one drives the response.

Vector Solutions and Frontline have partnered to provide a suite of industry-leading software solutions for law enforcement, including training management systems, online training courses, FTO and live skill evaluations, academy automation, asset and fleet management, shift scheduling, body-worn camera audits, community policing engagement, policy management, early intervention and professional standards, performance management, and accreditation management.