In a study a mock jury would be given the crimes of individuals and occasionally also a photo. When no photo was given the average sentence was 5 years which was the same for when a photo independently rated as “unattractive” was provided. With an attractive photo this sentence was just 3 years.
In another study subjects were assigned to one of 4 groups and presented with the same video of a boy in school. One group would be told nothing about the boy, whereas the others were each given varying understanding of a supposed mental deficit. Evaluations of the child’s performance were skewed significantly by this prior “knowledge”.