Psychology Weekends: Why We Tend To Presume A Criminal Suspect is Guilty

For this inaugural weekly post on psychology, I want to explore a topic that has intrigued me for a long time: the tendency to assume suspects are guilty of the crimes they’re charged with. I hear, with some frequency, the basic sentiment that people arrested of crimes are probably guilty. People say things such as “why would the police arrest him if he weren’t?” or “he looks like he did it” or things of a similar nature. Of course, these are snap judgments made by uninvolved people…not informed decisions of jurors who have heard evidence from both sides and come to a reasoned decision. Why does this happen? Why are people quick to presume guilt…particularly when they have such limited information (i.e. that which they hear, see, or read in media)? That’s the topic I want to delve into. This is an informal piece where I’ll propose a set of possible factors at play based on a review of known psychological phenomena.

1. A Hypothetical

Let me start with a scenario. A rash of break-ins occurs in a middle-class neighborhood of your city. Over the past couple of weeks, almost a dozen good, honest, hard-working people like you have had their privacy invaded and their possessions stolen. The hot items tend to be electronics (e.g. flat screens, blu-Ray players, laptops) and cash. Less frequently, jewelry goes missing. A vast majority of these break-ins occur during the day and when the homes are unoccupied.

The local news outlets have all been reporting on this disturbing trend. Then, one day the media announce that police have made an arrest in connection with the burglaries. A shot of the perp in cuffs appears on the TV along with a sound bite from the local police head saying: “We got him!”

Okay, now let’s pause. How do you feel?

Yes, yes, I know this is just a hypothetical but I have little doubt you’ve come across real-life scenarios that are quite similar to what I described above. So, how does that make you feel? I’m probably not too far off the mark to guess that it made you feel relieved. And why would you feel relieved? Because you presumed that the person who posed a threat to people like you (i.e. good, honest, hard-working people) is now in custody and you won’t be at risk of a break-in yourself.

Your assumption is in opposition to law. Any person who is charged with a crime is legally presumed innocent. The United States Supreme Court said so way back in the 19th century, at which point the presumption of innocence was already deemed “undoubted law, axiomatic and elementary … .” Coffin v. United States, 156 U.S. 432, 453 (1895). Now, if we wanted to we could get into an extended discussion of what it means to be found legally guilty of committing a crime because there is, after all, a distinction between whether a person acted in a certain way and whether such action would subject them to criminal penalty. Honestly though, I don’t want to get bogged down in that discussion. What I’m interested in is a discussion of why we tend to believe did what they’re accused of doing.

2. Basics of Ingroup / Outgroup bias

It seems to me that at least part of the reason people tend to assume a criminal suspect’s guilt has to do with the basics of “ingroup” and “outgroup.” There is plenty of research in the literature on the topic of the ingroup and the outgroup and the basic effect is that we tend to prefer people we view as similar to ourselves and we tend to dislike people who are dissimilar. Thus people like us are a part of the ingroup and people we view as different are a part of the outgroup. Researchers have provided evidence that we often see members of our ingroup as being more diverse while we often perceive outgroup members as being much more similar to each other (termed outgroup homogeneity bias). This is the essential psychological mechanism at play when we say people of a different race “all look the same” (Ackerman et al., 2006). Jost and colleagues (2004) provide a decent review of some of the major implications for those wishing to get up to speed.

As Ackerman (2006) also rightly noted, the outgroup homogeneity bias is a function of our reliance on heuristics. Rodin (1987) provided a series of experiments about how we allocate our cognitive resources and “disregard” things and people that we are not interested in paying much attention to. In other words, “[w]hen there are multiple events or stimuli competing for limited attentional resources, attention is mainly allocated to those that are most informative or suprising” (Rodin, 1987: 146).

Now let’s apply this. The label of “criminal” is a way of categorizing people—presumably people in your outgroup. I’m guessing you likely don’t view yourself as a criminal. In fact, you probably don’t consider yourself a criminal even if you have had some trouble with the law in the past. Say you got a DUI once or maybe when you were a kid you were charged with trespassing. It was a slip-up, a limited circumstance. You’re not a criminal, just a person who made a mistake. Of course, if you’ve never been charged breaking the law before then your belief in yourself as someone who isn’t a criminal will be doubly true.

Similarly, you probably aren’t arrested very often if ever. Again, some of you might have had a minor incident here or there but that’s it. So, when you see someone on TV in handcuffs it’s hard to relate to that.

From every angle, your conception of yourself as being different from a “criminal” helps create an “outgroup” mentality. People like you don’t do bad things nor do the police hassle your or arrest you. Therefore, the people who are arrested must be different. They must be in the outgroup.

3. Trusting Authority’s Ability to Get the Right Guy

The next component that I think goes into a tendency to presume a criminal suspect’s guilt is our pre-disposition to trusting certain authority figures. As Glanville and Paxton (2007) demonstrated, our tendency to trust is influenced in large party by social learning. That is, we learn based upon our particular life experiences whether people are generally trustworthy or not. This general method of forming trust can apply to the government and its actors. For example, concerns over security relate to our willingness to trust government. This has been particularly clear in the context of our response to government after 9/11 (Chanley, 2002). And, as one political philosopher / psychologist has described it, “when in doubt, follow a lead” (Searing, 1995: 680). Indeed, Searing (1995) might agree that a small portion of our trust is reciprocity-based; that we reward the government when it keeps us safe by giving it our trust.

So again, some application. The police say that they have caught a burglar or a bank robber. We assume that they are acting in good faith…that they have pieced together evidence and leads to find the right guy and place him under arrest.

4. Why Trusting Authority’s Ability Is Problematic

Here’s why that’s a bad thing to assume. Police are not necessarily any better at figuring out if someone is guilty or innocent than you are. Kassin and colleagues (2003) have examined the ability of police to successfully determine guilt through a series of experiments. Drawing on the work of Akehurst et al. (1996), Ekman & O’Sullivan (1991), and DePaulo & Pfeifer (1986), Kassin sought to confirm the fact that police “hold many false beliefs about the behavior indicators of deception and that groups of ‘experts’ who make such judgments for a living … are highly prone to error” (Kassin et al., 2003: 188).

The result? He found that investigators with “guilty expectations” not only were predisposed to interpret behavior and responses by suspects as indications of guilt but that it led them to utilize interrogation techniques “which constrained the behavior of suspects and led others to infer their guilt—thus confirming the initial presumption” (Kassin et al., 2003: 199). In other words, police and other law enforcement seem particularly prone to confirmation bias. Confirmation bias is the effect of interpreting information in a way that “confirms” your preconceived belief. For example,  a person who dislikes Chevrolets is most likely to give stronger weight to negatives that he learns about the brand. He is less likely to pay attention to, or give equal weight to, positives about the brand. In sum, Kassin and colleagues suggest that this tendency on the part of law enforcement to come into the interrogation room already thinking they have the right guy causes them to act in a way that both makes them particularly prone to confirmation bias and probably in a way that subjects a criminal suspect to high levels of coercion at the same time. The problem with coercion is, of course, that it has reliably translated into false confessions because suspects think saying what police want to hear will help them end the encounter.

In other words, investigators are every bit as prone to bias and getting it wrong as you and I are. What’s worse, there is some evidence to suggest that a suspect’s attempt to explain his innocence or present another story will not only be disregarded but may actually be used as further evidence of his guilt. Kassin observed that “it appears that [investigators] interpreted [an innocent person’s] denials as proof of a guilty person’s resistance—and redoubled their efforts to elicit a confession.” (2003: 200). This observation aligns with new research from Esposo and colleagues (2013), which illustrates we generally refuse to legitimately consider the possibility that a person’s argument is correct when that person is a member of an outgroup.

5. Concluding Remarks

In this post, I’ve put forward the mechanisms that seem to be at play in our tendency to presume a criminal suspect is guilty. I have not come across research that empirically tests precisely how common it is for us to consider an arrested person guilty nor any articles that have proposed models for the seeming effect. Accordingly, this is my informal and original suggestion of what is probably going on…or at least what known psychological tendencies probably play a role.

I have suggested that many people who presume criminal suspects guilty do so because they view “criminals” as members of an outgroup and because they are willing to trust that police do a good job of catching the right guys. I then have illustrated why there is strong psychological evidence to suggest that law enforcement aren’t necessarily that good at figuring out who is guilty versus who is innocent and reviewed studies explaining why.

For the most part, I aimed to keep this post descriptive rather than normative. I didn’t set out to g on a long tirade about how awful people are for presuming everyone is guilty rather than following the grand tradition of “innocent until proven guilty.” However, I do think at this point it’s appropriate to remind ourselves of a valuable college lesson: be a critical thinker.

We have a lot of information we have to process every day. It’s overwhelming and it’s lead us to, quite understandably, use short-cuts for processing. These heuristics let us parse all the data we receive quickly and efficiently. We put people into ingroups and outgroups. We make generalized determinations about who to trust. All of this saves us time and psychological energy. Unfortunately, it’s also lazy and dangerous. When a person’s liberty is at state—as it is with the criminal suspect—we owe it not just to them but to ourselves to be critical thinkers. This is something we owe ourselves because the legitimacy of our justice system depends upon it. The respect of process and justice that we desire can only come from us treating such judicial mechanisms seriously and giving them a rigorous foundation to rest upon. Our ability to think through things carefully, critically, and rationally is not in question—our ability to be disciplined enough to actually behave in such ways is. If we are willing to treat matters like guilt an innocence with proper gravity than we have gone a long way to ensuring that our system is fair and just. And a system that is fair and just is good for all of us.

-Zachary Cloud


Ackerman, J., et al. (2006). They All Look the Same to Me (Unless They’re Angry): From Out-Group Homogeneity to Out-Group Heterogeneity. Psychological Science, 17, 836-840.

Akehurst, L., Kohnken, G., Vrjj, A., & Bull, R. (1996). Lay persons’ and police officers’ beliefs regarding deceptive behaviour. Applied Cognitive Psychology, 10, 461-471.

Chanley, V. (2002). Trust in Government in the Aftermath of 9/11: Determinants and Consequences. Political Psychology, 23, 469-483.

DePaulo, B. & Pfeifer, R. (1986). On-the-job experience and skill at detecting deception. Journal of Applied Social Psychology, 16, 249-267.

Ekman, P. & O’Sullivan, M. (1991). Who can catch a liar? American Psychologist, 46, 913-920.

Esposo, S., Hornsey, M., & Spoor, J. (2013). Shooting the messenger: Outsiders critical of your group are rejected regardless of argument quality. British Journal of Social Psychology,  1-10

Glanville, J. & Paxton, P. (2007). How do We Learn to Trust? A Confirmatory Tetrad Analysis of the Sources of Generalized Trust. Social Psychology Quarterly, 70, 230-242.

Jost, J., Banaji, M., & Noesk B., (2004). A Decade of System Justification Theory: Accumulated Evidence of Conscious and Unconscious Bolstering of the Status Quo. Political Psychology, 25, 881-919.

Kassin, S., Goldstein, C., & Savitsky, K. (2003). Behavioral Confirmation in the Interrogation Room: On the Dangers of Presuming Guilt. Law and Human Behavior, 27, 187-203.

Rodin, M. (1987). Who is Memorable to Whom: A Study of Cognitive Disregard. Social Cognition, 5, 144-165.

Searing, D. (1995). The Psychology of Political Authority: A Causal Mechanism of Political Learning Through Persuasion and Manipulation. Political Psychology, 16, 677-696.


One response to “Psychology Weekends: Why We Tend To Presume A Criminal Suspect is Guilty

  1. Those of us who do not count on law enforcement or prosecutors to support us, or validate us, know the truth; people are arrested for a reason. The arrest can be an illegal arrest, a vendetta, a set up, or it might be valid . The people who believe what they read are ignorant of how the machine works.

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