The subjective sense of national identity is a complex psychological structure. At the cognitive level, it involves knowledge of the existence of the national group, knowledge of the national geographical territory, knowledge of the national emblems, customs, traditions, historical events and historical figures which symbolically represent the nation, beliefs about the typical characteristics of members of the national group, and beliefs about how similar the self is to the national type. At the affective level, the sense of national identity involves a subjective sense of belonging to the national community, feelings towards the people who make up the national group, numerous social emotions such as national pride and national shame, and an emotional attachment to the national homeland.

The acquisition of this complex system of knowledge, beliefs and feelings takes place over a period of many years spanning both childhood and adolescence. At the University of Surrey, we have been conducting a systematic programme of research to investigate how this subjective sense of national identity develops during the course of childhood and adolescence.

In a number of studies, we have found that children are able to talk about their membership of their own national group by 5 years of age. In addition, we have found that the importance which children attribute to their national identity increases significantly between 5 and 11 years of age. The degree of perceived similarity between the self and the national type also increases between these ages. We have further found that at 5 years of age, children often feel very positively about the people who belong to their own national group, and far less positively about foreigners. However, between 5 and 11 years of age, children's descriptions of the people who belong to their own national group gradually become less positive, as they begin to ascribe more variability and more negative traits to the members of their own national group. By contrast, across this same age range, children's descriptions of the people who belong to other national groups become more positive. These findings suggest that children's preference for their own national ingroup, and their prejudice against national outgroups, are at their strongest early in middle childhood, with the strength of these biases declining as children approach adolescence.

In other studies, we have examined children's knowledge of national emblems and their knowledge of national geographical territory. For example, we have explored whether national geographical knowledge is related to the sense of national identity in children. Our studies here have revealed that national geographical knowledge increases significantly between 5 and 11 years of age, and that the amount of national geographical knowledge which children acquire is indeed positively correlated with their sense of national identity.

Other findings have come from two cross-national programmes of research which are being coordinated from the University of Surrey. These research programmes are being conducted in collaboration with colleagues in Scotland, Spain, Italy, Russia, Ukraine, Georgia and Azerbaijan. In both of these larger studies, we have collected data from children and adolescents aged between 6 and 15 years old. By using cross-cultural designs, we have been able to identify those aspects of development which remain constant irrespective of the child's sociocultural context, and those aspects which vary as a function of context. We have found that ingroup favouritism, especially in young children, is a widespread phenomenon, irrespective of culture. In addition, some of the general age trends identified in our other studies (for example, the changes in the importance which is ascribed to national identity, and the changes in the perceived similarity between the self and the national type) do occur in most groups of children; however, these general age trends are exhibited to a different extent by different groups of children, apparently as a function of the specific sociocultural context in which the children are growing up. Furthermore, these differences in the development of different groups of children typically become more pronounced during adolescence.

These findings imply that the development of national identity is driven not only by the cognitive changes which occur to the way in which the child is able to conceptualise the social world at different ages, but also by social influences. Thus, many of the changes which occur between 5 and 11 years of age are probably a consequence of the child's increasing ability across this age range to conceptualise large-scale social groups such as national groups. At the same time, however, the way in which even these cognitively-driven changes are expressed within any given child is modulated and affected by the specific sociocultural setting within which the child lives.

We are currently expanding the focus of our research to include not only the development of national identity but also the development of ethnic and religious identity, in order to explore how these other identities impact upon the development of national identity in children.