Funded by the Economic and Social Research Council (ESRC), a study into the 'black sheep effect', shows that children treat disloyalty in their own group more harshly than disloyalty within different groups.
Professor Dominic Abrams, of Kent University, who led the research team, says the findings will be valuable when applied to the classroom.
"This research has implications for peer victimisation and bullying as well as for the understanding and management of prejudice and discrimination in schools," he said.
The research suggested that children progress from regarding groups of people in simple terms of difference, such as White or Black, to regarding people more as unique individuals. However, it does not easily explain why prejudice happens at different ages for different types of groups or why adults continue to show prejudice.
The new research was stimulated by evidence that adults may show strong bias in favour of or against groups while also being staunch critics of individual members within those same groups. Rather than becoming less prejudiced with age, young people can grow to support their own group in a more targeted and sophisticated way. They focus not just on whether peers belong to their own group, but on how well they conform to social values, such as loyalty to the group.
A series of 7 experimental studies, which was carried out on more than 800 children aged between 5-12, showed that children in this early age group favoured loyal peers more if these peers belonged to the same group as themselves than if they belonged to a different group. Disloyalty within outside groups was seen to be more valued and not criticized in the same way as it would be from members of their own group. This "black-sheep effect" was found within national groups (French and English) and within gender groups where it was clearer for boys than girls.
The research consistently supported a new model, known as the Development Model of Subjective Group Dynamics, challenging previous theories of childhood prejudice.