Abstract
Frequency of child social interaction with peers has been criticised as a measure lacking in concurrent and predictive validity. In the present paper it is suggested that this criticism arises in part from a failure to differentiate the behavioural and conceptual features of social isolation and social withdrawal. Definitions of child social isolation and social withdrawal are here derived from a reinterpretation of published data and it is shown that low rate of interaction with peers is empirically and logically related to the concept of social withdrawal. Suggestions for establishing the concurrent and predictive validity of frequency of peer interaction measures are given and a case made for further research into interventions for children who show low levels of involvement with peers.