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Potential Biases in Police Decision-Making

The problem with being human.

Key points

  • Human beings make decisions in two ways. System one is quick and reactive, whereas system two is more deliberative.
  • System one thinking can serve us well but can also lead to bad and erroneous decision-making.
  • Police officers are humans and so make decisions using the same equipment as the rest of our species.
  • Police errors in decision-making due to cognitive bias are predictable and so avoidable.

I am a psychologist who has worked with police in the areas of applied research and consultancy for more than two decades now, predominantly with UK police but also with police in other parts of the world including the U.S., Norway, and Denmark. My work looks at those charged making difficult decisions in policing—whether that be in relation to trying to prevent and stop crime or to identify, detect, and bring to justice detecting those who commit it, such as front-line police and criminal investigators.

Curiously, police decision-making still receives much less attention from academic research than either "criminal psychology" or "how criminals make decisions." This is somewhat surprising if, like me, you consider that those who commit crime and those who try to prevent and stop it are surely two sides of the same coin.

Why Does Police Decision-Making Matter?

In what contexts do police make decisions? What decisions must they make? What is the psychology behind "good" and "bad" police decision-making? These are questions that motivate my work. The fact that police are human beings means that they have to rely on the same brain design, structure, and cognitive processes as the rest of us. An appropriate starting point, then, is to explore human decision-making processes in general, before moving to human decision-making in a policing and crime context.

The decisions we make can be influenced by an infinite number of different factors such as context and situation, our personalities, previous experiences, or whether we feel hungry or tired, to name a few. Evolution has provided us with incredibly powerful brains capable of thinking in two main ways: instant decision-making, referred to as "system one thinking"—more commonly referred to as "intuition"—and a more conscious and deliberate process known as "system two" thinking, which allows us to put the "cognitive brakes on" to think about something in a slower and more deliberative way (Kahneman, 2011).

System two is therefore the more rational, calculating, "risk-reward weigher-upper" way of thinking and making decisions. Alas, system two cannot guard completely against making "bad" or erroneous decisions, even if we do actively choose to employ it. Infallibility is beyond even our amazing brains.

System one thinking is to some degree shared with most of the animal kingdom, because survival generally depends on reacting quickly to a present danger in order to live and avoid becoming another animal’s dinner (as any wildlife documentary will testify). Slow decision-making in such hunter and prey scenarios is not a recipe for longevity—hence, much of our decision-making is immediate and cognisant of "fight or flight" fame. (This despite us not having any natural predators any more; hungry lions may, for most of us anyway, be way down the list of daily risks we are exposed to, compared with risks posed by fellow humans.)

That said, this quick "system one" thinking may serve us well in most decision-making contexts—particularly where time is at a premium. But it can be our downfall in others. Police decision-making is no exception to this general rule.

Is System Two Thinking the Answer?

System two thinking gives us another decision-making option. As stated earlier, this will not protect us completely from making a wrong or ridiculous decision, especially at times when all the options available to us appear to be unsuitable and we actually look to choose the "least-worst option."

Let those of us who have made a recent wrong decision take solace in Guy Bellamy’s reminder in The Sinners Congregation that "hindsight is an exact science" (1982). It might be the only one, too, with hindsight often feeling that it illuminates our mistakes and errors brighter than the brightest star in the night sky—or at least brighter than any decision we got right. In short, we shouldn't hard on ourselves for being human—and police decision-makers are human, too.

In future posts, I'll aim to demonstrate how relying on system one thinking can have a negative influence on police decision making and how they (and us) might guard against this. By way of a quick example, look at the pictures below and answer the following question as quickly as possible: Why do you think that the police have been called to each of these two buildings?

Vladimir Kudinov/Pexels
High-rise apartment block
Source: Vladimir Kudinov/Pexels
Olga Lioncat/Pexels
Detached house
Source: Olga Lioncat/Pexels

If you employ only system one thinking, you might be more likely to assume the police presence at the high-rise tower block is for "enforcement" reasons—that is, to arrest someone for a crime like burglary. For the nice detached property (in a nice residential area) you may be more likely to see police attendance as performing a more supportive role—for example, to investigate a burglary and to support the victims residing there. This pattern is what we found in a study we conducted a few years ago (Roach, Brown and Pease, 2012).

If you engage your system two thinking, then you will likely question your first impressions and see that your answer is biased by your opinion of the sort of people that you think reside in each of these types of residence—that is, that a high-rise dwelling is more likely to house an offender than the nice detached house in a nice area of town, who are more likely to be victims of crime. But why should this be the case, when domestic violence, for example, is perpetrated by some people irrespective of their socio-economic status or the building at which they reside? Indeed, this might be why the police have been called to the nice detached property and not because its inhabitants have been victims of crime.

This is the kind of everyday scenario that police routinely encounter and one where system one bias can negatively influence police decision-making if it goes unrecognized and unchecked. Although we shall explore other potential cognitive bias effects on police decision-making in future posts, we will also highlight good police and investigative decision-making, of which there is much.

Stay safe.


Bellamy, G. (1982). The Sinner’s Congregation. London: Penguin.

Kahneman, D. (2011). Thinking Fast and Slow. London: Allen Lane.

Roach, J., Alexander, R. and Pease, K. (2012) ‘Signal Crimes and Signal Policing’ The Police Journal, 85 (2), pp. 161-168.