Biases in first impressions, and how to be fair about them

Research on photos of faces finds that people form a trait impression in about a tenth of a second, and then may spend the rest of the conversation either checking it or being steered by it. Whether that carries over to real conversations is less clear. It cuts both ways: the people you meet are judging you just as fast, and so are you judging them.

Knowing the common biases doesn't remove them. It does make it easier to catch yourself deciding too early, which helps when you meet someone new and when you replay a conversation afterward.

How fast impressions form

In a 2006 paper in Psychological Science, Willis and Todorov showed people unfamiliar faces for 100, 500 or 1,000 milliseconds across five experiments. Judgments of attractiveness, likeability, trustworthiness, competence and aggressiveness made after 100 ms correlated highly with judgments made with no time limit. More time mostly raised people's confidence in their judgments, not the judgments themselves, though longer exposure did produce more differentiated impressions.

A caution. These were ratings of photos of faces, not conversations. And speed isn't accuracy. A 2015 review in the Annual Review of Psychology by Todorov and colleagues found that people agree with each other about what traits a face suggests, yet argued that the diagnostic validity of these face-based judgments has been greatly overstated. People agree on what a face seems to say. That doesn't mean the face is right.

The halo effect

The halo effect is when one standout trait colors your view of everything else about a person. In a classic 1972 study, as summarized by the FORRT open-science project, Karen Dion, Ellen Berscheid and Elaine Walster found that physically attractive people were assumed to have happier social lives and more professional success than less attractive people. A later and broader check came in 2000, when Langlois and colleagues ran 11 meta-analyses and reported that attractive children and adults were judged more positively, even by people who knew them.

The same logic applies in reverse and with other traits. A confident voice, a nice jacket or a famous employer can work as a halo. A nervous laugh or a scuffed shoe can work as the opposite.

Similarity feels like attraction

Similarity is one piece of how attraction works, and people tend to like those who seem similar to them. Montoya, Horton and Kirchner pooled 460 effect sizes from 313 studies in 2008. Both actual similarity (r = .47) and perceived similarity (r = .39) were linked to attraction. The pattern changed with familiarity: actual similarity mattered in studies where people had little or no interaction, but in existing relationships its effect wasn't significant, while perceived similarity still predicted attraction. These are correlations, so they can't say which causes which.

For first impressions, the practical point is that you may like someone partly because they mention the same band, and dismiss someone partly because their taste differs on something small.

Expectations steer the conversation

In 1977, Snyder, Tanke and Berscheid had men talk on the phone with women after seeing a photo that supposedly showed their partner (described here from FORRT and Psychology Today summaries, not the original paper). Some photos had been rated as attractive and others as unattractive. Outside listeners who heard only the women's side rated the women whose callers had seen the attractive photo as more sociable, sexually warm and poised. The authors read this as a self-fulfilling expectation: the men's beliefs shaped how the conversation went, which then seemed to confirm those beliefs.

The study is famous, and it's old and about one setup, so the effect size in everyday life isn't known. A follow-up by Andersen and Bem in 1981, as FORRT summarizes it, found that the pattern depended on the participants' gender roles. It's best read as a demonstration that expectations can change behavior, not a measurement of how often they do.

Impressions change, and they're noisy

Two findings help.

Consensus fades with knowledge. Eastwick and Hunt found in 2014 that agreement between raters about who was appealing dropped as they got to know each other better. What you see in the first minute is a thinner version of what you'd see after a month.
The same person looks different from one moment to the next. Hehman, Flake and Freeman found in 2015 that judgments of a person's intentions varied a lot across different pictures of the same face, while judgments of ability varied less. A flat moment, a bad photo or a tired day can shift how someone comes across.

Being fair to the other person

These are habits, and none of them is a proven fix.

Separate what you saw from what you concluded. "She answered in one word" is an observation. "She's not interested" is a conclusion. Write them separately. Body language follows the same split: a crossed arm is an observation, what it means is a conclusion, and reading other people's body language gets easier once you keep the two apart.
Hold the verdict for one more question. Ask something open, like "what's been the best part of your week?" and see what you get. Building rapport in the first ten minutes covers this.
Notice your halos. If you're drawn to someone fast, ask what you're assuming about them. If you're turned off fast, ask the same.
Give a second look. If you're unsure, meet once more in a different setting before deciding.

Being fair to yourself

People tend to underestimate how much others like them after talking. In a 2018 study in Psychological Science, Boothby, Cooney, Sandstrom and Clark observed this "liking gap" with strangers in the lab, first-year dorm mates and workshop attendees, and in some cases it lasted for months. So your post-conversation worry that it went badly may be too harsh. You can't control how fast someone judges you, but some inputs are yours, such as eye contact and a relaxed pace. For the visible side, see how to be more attractive, and stop taking rejection personally if a flat first meeting is weighing on you.

What to do next

After every conversation, write two lines. What did I observe? What did I assume?
Spot one halo a day. Notice a time a single trait changed your view of someone, good or bad.
Ask one open question before deciding. Wait for a full answer.
Give a flat first meeting a second chance when it's low-risk. A coffee, not a night out.
Stop replaying for a day. Check your read the next day, once you're not still in your head.
Check your own interactions for the liking gap. Ask a friend or a match how the conversation felt to them.

If you log approaches in Run Game, putting your observation and your guess in the notes as two separate lines makes it easy to see later which guesses held up.