Would You Trust a Stranger? Your Brain May Decide Before You Do

Think about the last time you met someone for the first time. Before they even finished introducing themselves, you probably had some kind of impression. Maybe they seemed friendly, confident, nervous, or trustworthy. Or maybe something about them immediately made you uneasy. The strange part is that you may have formed that impression before you consciously decided what you thought of them.

Research from Princeton University found that people can form impressions of an unfamiliar face after seeing it for just 100 milliseconds. Participants made judgments about characteristics including trustworthiness, competence, attractiveness, and likeability after such a brief exposure, and those initial judgments were surprisingly similar to judgments made when participants were given unlimited time to view the same faces. 

So what happens when that stranger isn't someone you happen to meet at a party, but a defendant, plaintiff, attorney, or witness sitting in a courtroom?

First Impressions Happen Fast

Jurors don't walk into a courtroom as blank slates. Before they hear the evidence, they see the people involved in the case and take notice of how someone speaks, dresses, moves, reacts, and carries themselves. Those observations may begin shaping perceptions long before the jury reaches a verdict.

And importantly, a first impression isn't necessarily an accurate impression. Researchers from Princeton University have found that people can make remarkably consistent judgments about whether a face looks trustworthy, but that doesn't mean those judgments accurately reveal a person's actual character. 

That distinction is incredibly important in a courtroom. A nervous defendant may look suspicious when they are simply anxious. A witness who avoids eye contact may appear evasive even though eye contact isn't a reliable measure of honesty. An attorney who speaks with confidence may be perceived as more credible, even when confidence itself tells us very little about whether an argument is correct.

In fact, research from “Non-verbal cues in eyewitness testimonies do not predict accuracy or credibility assessments” examining eyewitness testimony found that nonverbal behaviors were not reliably associated with either accuracy or perceived credibility, despite the importance people often place on those cues. The perception, however, can still be there.

When Perception Follows Jurors Into Their Decisions

This becomes more concerning when we consider what those impressions can actually influence.

Princeton researchers have specifically studied whether facial impressions affect legal decisions. In a series of studies involving thousands of participants, researchers found that facial trustworthiness stereotypes could influence verdict decisions. In the study, facial features in relation to trustworthiness were identified as the following: 

Trustworthy Facial Features

• Mouth Shape: Slightly upturned mouth corners (resembling a subtle smile or positive emotion).

• Eyes & Eyebrows: Rounder, larger eyes and neutral-to-higher eyebrows.

• Babyfaced Traits: Softer facial structure, rounder face shape, and smaller chin/jawline.

Untrustworthy Facial Features

• Mouth Shape: Downturned mouth corners (resembling a subtle frown or negative emotion).

• Eyes & Eyebrows: Narrower eyes and lowered, inner-slanted eyebrows forming a subtle "V" shape (resembling anger).

• Facial Structure: Harsher, sharper angles and prominent facial dominance cues.

In one study, defendants with untrustworthy-looking faces were found guilty more often than defendants with trustworthy-looking faces. Even when participants were educated about facial stereotypes, the researchers found that the bias was not completely eliminated. 

That doesn't mean jurors aren't capable of carefully evaluating evidence. It means that people's perceptions can influence how they process the evidence in the first place. And the same principle applies beyond the defendant, such as expert witnesses. Research on expert witnesses, for example, has found that likeability can influence perceptions of an expert's trustworthiness. Other research examining witness credibility has identified factors such as knowledge, likeability, trustworthiness, and confidence as important dimensions of how witnesses are perceived. In other words, jurors aren't just evaluating what someone says but inevitably responding to the person saying it.

Then There's Social Media

This is where first-impression research becomes particularly interesting for jury research. Jurors don't exist only inside the courtroom. Before trial, jurors have spent years building digital footprints through social media and other public online activity. That information can provide additional context about who they are, what experiences may have shaped them, and how they may perceive the people and issues involved in a case. 

But here's the catch: the person we see online isn't necessarily the person we think we're seeing. Researchers at Cornell University found that people's impressions of others based on Facebook profiles could differ substantially from how those individuals described themselves. Their research also found that photographs, videos, and other multimedia could help observers make more accurate personality assessments, while simultaneously producing greater variation in how different people perceived the same individual. That is exactly why social media research can be so valuable and why it needs to be approached carefully. 

A single post might tell a researcher something about a potential juror, but it shouldn't automatically become a conclusion about that person's beliefs or ability to be fair. A photograph from a political event, for example, is a fact. Concluding that the juror therefore cannot fairly evaluate a particular case is an interpretation.

The more useful question is whether patterns emerge. Does the juror repeatedly discuss the same issue? Do their posts show years of consistent opinions? Does their professional or personal experience overlap with the facts of the case? And perhaps most importantly, how might those experiences shape the way they perceive the people sitting in front of them?

The Researcher's First Impression Matters, Too

There is an interesting irony here. Jury research is designed to help litigation teams understand jurors, but researchers are human, too. We are just as capable of looking at a social media profile and quickly creating a story about the person behind it.

That's why good jury research has to go beyond collecting interesting facts. The objective in jury research is to look at the broader picture, distinguish fact from interpretation, identify meaningful patterns, and consider how those patterns could affect the way a juror receives the evidence and the people presenting it.

The Federal Judicial Center has studied attorneys' use of social media during voir dire and specifically identified concerns surrounding juror privacy, potential intimidation, and the possibility that information found online may not be accurate. That last concern is particularly important as information can be completely real and still be easy to misinterpret.

What Happens Before the Evidence?

The science of first impressions doesn't suggest that jurors are incapable of being fair. Instead, it gives trial teams something important to think about: jurors are human beings making judgments in a highly human environment. They may form impressions of a defendant before hearing the evidence, may decide a witness seems credible before hearing the full testimony, may respond differently to an attorney based on communication style, and may arrive at jury selection with years of experiences and beliefs that influence how they perceive the people and issues in front of them. Social media research can provide another layer of context for an important question: What might this juror see when they look at the people sitting in this courtroom?