What assumptions do we make about people when we first meet them?

Most personality traits and other characteristics are "normally distributed", meaning that a new person is more likely to be in the middle than on the extremes, whether we're talking about extraversion, intelligence or enthusiasm for Mexican food. So when you're getting the measure of a stranger, a good bet is to assume that they're pretty average. That would be the rational approach when forming first impressions, but a new paper in the Journal of Personality and Social Psychology has looked into whether this is something people actually do.

In total, the researchers Katherine Rogers and colleague Jeremy Biesanz tested eight different samples totalling over 2000 undergraduate students on two tasks. The first was a (platonic) speed-dating exercise, where participants spent three minutes getting acquainted with a stranger, then assessing their personality before moving on to another partner, in groups of up to twelve. For the other five samples, the activity was to watch different individuals talking on video, and then to assess their personality based on the few minutes of footage.

This isn't an easy topic to study because when it looks like someone is relying on the idea of the "typical" person, they might instead be assuming that a stranger has a socially desirable character. The two approaches are confounded because more typical personality profiles are usually also seen as more socially desirable.

For this reason the researchers were particularly interested in ratings for traits that aren't seen as similarly typical and desirable. For example, they focused on how the participants rated others in terms of how organised they seemed. This is because being "easily distracted" is usually seen as just as undesirable as being "disorganised", and yet being easily distracted is seen as more typical of most people.  Looking at these ratings therefore helped the researchers to disentangle whether people generally assume someone they've just met is an average character or a socially desirable character.

It turns out that both strategies get used, in distinct ways. We presume people are typical, and also presume that people are socially desirable, and sometimes we do both. A difference arose across the two types of study: in the video experiments, participants leant on knowledge of what the typical person was like to round out their assessments of the filmed subject. But in the speed dating studies, impressions were steered by both what's typical and what's desirable. This suggests that we're more likely to make favourable (as opposed to exclusively average) assumptions about someone after we've had an active interaction with them. This actually lines up with past research showing that passive viewing of a person leads to attenuated liking: we take a more alienated, mechanical view of the person, rather than allowing them to arouse our spirits.

In the speed-dates, why did some participants rely more on normality and others more on social desirability? It seemed to come down to whether people had a better understanding of what's typical or of what's desirable. Some participants were more accurate in plotting out what the average personality profile looks like, and they were the ones more likely to rely on this, not social desirability. And exactly the same was true for social desirability. It seems we make associations based on what we have experience of and prefer to orient towards.

So, how do we fill in the blanks when judging someone unfamiliar? Some people do it poorly, relying on wild assumptions – "everyone is out to rob each other" – but most of us are accurate, but in different ways, relying on notions of normalcy or desirability depending on our own tendencies and the situation at hand.

Further reading

Rogers, K., & Biesanz, J. (2015). Knowing versus liking: Separating normative knowledge from social desirability in first impressions of personality. Journal of Personality and Social Psychology, 109 (6), 1105-1116 DOI: 10.1037/a0039587