A single instance of unusual behaviour by a minority group may be enough for us to stereotype the whole group according to recent research published in the Personality and Social Psychology Bulletin.
Led by psychologist Jane Risen, the researchers ran four experiments that suggest that the reason we tend to think a single notable behaviour is typical of a minority group but not a majority group is because of our inbuilt cognitive biases in how we process anomalous information.
During the study participants were shown a series of sentences that described a group and a behaviour. The researchers found that just one report of a seemingly odd behaviour by a minority group member was focused on for longer and was more memorable.
Furthermore, participants were more likely to think that group membership was more like to be an explanation for the odd behaviour for minorities than in more representative groups.
In a final experiment, participants watched a video interview of either a white or Asian student where, rather unusually, they persistently asked to use the camera in a pushy manner.
Afterwards, the participants were shown a picture of another person, again either white or Asian. In one part the person was holding up words with missing letters than the participants had to fill in to complete the word.
For example, the prompt could have been “D E _ _ N D”, which can equally well be completed as “DEPEND” or “DEMAND”.
This sort of technique is often used in psychology because things that are already active in the mind, such as emotions, concepts or stereotypes, will unconsciously influence the participant to complete the word in one of the two ways.
DEPEND is a positive word, whereas DEMAND is related to pushiness, so if a video of a pushy Asian student only affects word completion presented by another unrelated Asian person and not when presented by a white person, you can see the behaviour has activated a race specific bias.
This is exactly what happened. The researchers confirmed the effect by a follow-up task where participants were asked to select interview questions for an unrelated white or Asian person, where they tended to select questions that enquired about how brazen the interviewee might be for the minority group.
This study was published in 2007 and I’ve only just discovered it. I’m surprised I’ve not heard of it before as it strikes me as an incredibly important study on the psychology of stereotype formation.
The researchers call it ‘one shot illusory correlation’ and I wonder if it also explains the ‘my bad holiday’ effect where people say they “don’t like the British [or whoever], because I went on holiday there once and someone was rude to me”.
Obviously, the person was not a minority in their country, but was in the context of the visitor’s life.
By the way, the paper is also very well written and the introduction is well worth reading solely for it’s engaging introduction to the area.
Mind Hacks 
It would be interesting to test these behaviours on people from various cultures. Our own culture is teaching us many biases based on nothing more than our group’s history. I tend to be very careful with this kind of generalization.